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Rear view of a Ford hydrogen hybrid SUV.

Plug-in electric vehicles. Hydrogen fuel cell cars. Hybrids. Plug-in hybrids. All have come to the fore over the years, and we’ve noted their unique impact on the automotive landscape. While these technologies share similarities in that they all employ different ways of managing electricity to power electric motors, it’s been pretty easy to draw lines between them. But what if those lines were blurred in the interest of creating a new and possibly better answer, like maybe…a plug-in hydrogen hybrid?

Actually, that question was on the minds of creative souls at Ford some 15 years ago. Back then, the automaker explored new paths with its Ford Edge HySeries, a drivable demonstration vehicle unveiled at the Washington, D.C. Auto Show.

Display showing operation of a hydrogen hybrid vehicle.

This Hydrogen SUV Plugs In

The HySeries combined power from the grid by plugging into an electrical outlet, just like an electric car or plug-in hybrid. It used a hydrogen-powered fuel cell to provide electricity, just like other fuel cell vehicles. And it managed its two power supplies via on-board battery storage, just like hybrid and plug-in hybrid cars do today.

Central to the HySeries Drive, both figuratively and physically, was a 336-volt lithium-ion battery pack that powered the electric motors at all times. Electricity from the grid and the fuel cell didn’t get to the wheels without first going through this battery pack. In this single-path flow of power, the power unit – the fuel cell – and the batteries were designed to act in series.

Illustration of a hydrogen hybrid drivetrain.

Series Versus Parallel Hybrid

With the notable exception of a few models like the Chevrolet Volt, in most hybrids the batteries and engine operate in parallel. That is, the engine can still directly send power to the wheels with the battery stepping in to provide boost or take over as necessary. These hybrids do periodically act like a series configuration by using the engine to charge the batteries back up, for instance. The difference is that the HySeries Drive runs exclusively in series mode…thus, the name.

What’s the advantage? In a word, simplicity, according to Ford at the HySeries’ auto show debut. Operating in series streamlined the process by eliminating the extra hardware – and complex management software – of two propulsion systems in favor of a single power flow. By the same token, this made the HySeries Drive remarkably versatile.

Hydrogen fueling inlet in a vehicle.

In the Ford Edge prototype presented here, the fuel cell acted as a range extender, providing electrical power when the batteries ran low on their grid-sourced charge. But that range extender could just as well have been an engine powered by gasoline or some other alternative fuel. The thinking was that any new fuel or propulsion technology could be swapped in as it became available, with the underlying architecture of the HySeries Drive the same in any case.

The Ford Edge with HySeries Drive was designed to demonstrate the logic of this approach. According to Ford, the size, weight, cost, and complexity of this particular drivetrain was reduced by more than 50 percent compared to conventional fuel cell systems at the time. By relying more on the battery pack and the grid-sourced electricity, the demands on the fuel cell system were reduced as well. This meant the Ballard-supplied fuel cell would last longer and less hydrogen would need to be stored on-board.

Ford Edge hydrogen hybrid SUV.

Hydrogen Hybrid Operation

Out on the road, the Edge was designed to drive 25 miles on battery power alone. When the battery pack was depleted to 40 percent charge, the fuel cell turned on and began generating electricity to replenish the batteries. The 4.5 kg of hydrogen stored in a 5,000 psi tank was enough to extend the range another 200 miles, for a total of 225 miles. Ford pointed out that range was highly dependent on driving conditions. In fact, it was also said that careful driving could potentially squeeze more than 400 miles from the fuel supply. Given that on-board hydrogen is now typically stored in 10,000 psi cylinders rather than the earlier 5,000 psi variants of the HySeries’ time, that driving range had the potential to be significantly greater.

Actual fuel economy would depend on the length of a trip. For those driving less than 50 miles a day, the Edge with HySeries Drive would be expected to return a miles-per-gallon equivalent of 80 mpg. Longer drives tapping further into the hydrogen supply would bring combined city/highway equivalent fuel economy down to 41 mpg, still respectable for a crossover SUV. Of course, while the fuel economy rating may have had a gasoline equivalent, the emissions did not. That is, there weren’t any emissions at all…at least not from the vehicle itself.

Ford Edge HySeries hydrogen hybrid.

As innovative as Ford’s HySeries Drive was, it was not totally unique. Also in 2007, Chevrolet showcased its Volta concept using GM’s E-Flex System, which later evolved into the Chevrolet Volt powertrain. Both Ford and GM approaches relied on a large lithium-ion battery pack operating in series with a separate power source that charged batteries when they ran low. Notably, both systems offered plug-in capability. While the HySeries incorporated advanced hydrogen fuel cell power, the Chevy Volta did not, though GM did share this was a future possibility. Rather, the Volta, like the production Chevrolet Volt to come, used a 1.0-liter gasoline engine as its range-extender,

Birth of the Plug-In Hybrid

What we saw in the Ford Edge with HySeries, the Chevrolet Volta, and other concepts to follow was the underlying development of a drivetrain showcasing a new propulsion category carving its place into the mainstream – the plug-in hybrid vehicle. At the same time, both GM and Ford seemed eager to link their conception of the plug-in hybrid to the trek toward hydrogen-based transportation, which at the time was the official long-term goal of these two major automakers and others. In this sense, the plug-in hybrid would conceptually follow the conventional hybrid as another intermediary step on the path to hydrogen power.

Rear view of the Ford HySeries hydrogen hybrid vehicle.

Of course, to expect such a simple, linear progression – gasoline, hybrid, plug-in hybrid, hydrogen – is, and was, naïve. But that’s the core challenge with predicting the future of any industry, or of life in general, for that matter. Emergent and divergent technologies, parallel paths, and new alternatives are guaranteed along the automobile’s evolutionary path. In particular, we have seen that in recent years with the breakout of all-electric vehicles into the automotive mainstream, in numbers that were not envisioned by most at the time the HySeries was revealed.

With the HySeries-equipped Edge, Ford presented a surprisingly realistic look at how HySeries Drive – or something like it – could one day take to the road. It sat on the cutting edge of a broad trend away from petroleum-burning internal combustion and toward electrically-powered transportation, a trend that is accelerating today.

Hydrogen fuel cell vehicle illustration.

Our journey of discovery with hydrogen vehicles started with the Mercedes-Benz’ fuel cell-powered NECAR II (New Electric Car II) in Berlin back in the mid-1990s. Since then, we have driven an array of hydrogen fueled vehicles from the world’s automakers on test tracks and on the highway. Along the way we have analyzed their capabilities and the strides being made in the hydrogen vehicle field over time, always impressed with constant improvement in their technology, cost, durability, component downsizing, and packaging.

What we’ve found in recent years is that hydrogen fuel cell vehicles drive like their more conventional counterparts, exhibiting satisfying levels of power and an overall positive driving experience. Their cabins are quiet, devoid of earlier developmental issues like gear whine or compressor noise. There is no sound or vibration from internal combustion because power is generated electrochemically without combustion. This electricity powers one or more electric motors that drive the vehicle, just like a battery EV. No greenhouse gases are produced and no emissions other than water vapor.

Driving the Equinox Fuel Cell

While there have been many important milestones over the years from the automakers pursuing hydrogen power, perhaps none was as notable as our experience driving GM’s Chevrolet Equinox Fuel Cell in 2007. At the time we knew the crossover we were piloting was one of the most advanced vehicles on the planet, Yet we set out on our drive chatting away with our GM guide almost oblivious to the high technology at work as we motored along, as if this was an everyday journey. That was a telling moment.

It may be that this crossover vehicle was fueled with hydrogen, created its power through an electrochemical process in lieu of combustion, and used the same kind of technology that created electricity and water onboard the Space Shuttle of the era. No matter. Driving it felt so normal . We were completely at ease during the drive with little thought of the processes at work behind the scenes. And that’s just what GM – and in fact, the entire automotive industry – was after. The deed was done.

It wasn’t always so, though developers of fuel cell vehicles had come ever-closer over the years. The ultimate goal was to create hydrogen fuel cell vehicles that disguised all the advanced technology at work. From the driver’s seat, some fuel cell vehicles leading up to our Equinox Fuel Cell drive were more seamless than others, like Toyota’s FCHV and Honda’s FCX. In many cases, though, developmental fuel cell vehicles functioned quite well but were still a degree of separation from production vehicles in certain areas.

Hydrogen Fuel Cell Challenges

Among the many challenges of the day was making the electrically powered drive-by-wire systems required in fuel cell vehicles act and feel like familiar mechanical systems of the day. At times, accelerator and brake pedal input routed through central control units felt a bit too much like on-off switches in developmental fuel cell vehicles. While otherwise eerily silent, high-pitched electric motor whine and sometimes fuel cell compressor noise were present. These challenges were being aggressively addressed as fuel cell vehicle development marched ahead, and they appeared fully resolved in the Chevy Equinox Fuel Cell crossover we were driving.

Soon after our time behind the wheel of the Equinox, drivers in suburban Los Angeles, New York City, and Washington D.C. also had the ability to experience these vehicles through the automaker’s “Project Driveway.” This program placed more than 100 Equinox Fuel Cell vehicles in the hands of private motorists ranging from regular families to celebrities. Drivers were provided free use of an Equinox Fuel Cell and the hydrogen fuel needed to run it for an average period of about three months. In return, participants provided GM feedback about the vehicles’ performance and their views about the experience.

Following our test drive of the Equinox Fuel Cell, , we were certain these advanced hydrogen vehicles would have no problems keeping up with the daily driving demands of Project Driveway participants. Plenty of space for four passengers and 32 cubic feet of cargo volume were afforded by careful packaging of GM’s fourth-generation fuel cell propulsion system, including a 1.8 kWh nickel-metal-hydride battery pack and three 10,000 psi hydrogen storage tanks.

Driving 160 Miles on Hydrogen

The Equinox Fuel Cell’s 160 mile driving range was designed to meet the needs of most driving chores. Sub-freezing operating capability was an additional advancement of particular importance to East Coast drivers. As is the case with most fuel cell vehicles, fueling up the Equinox with hydrogen was done in about the same amount of time as filling up a gasoline car. The hydrogen-powered Equinox Fuel Cell met the same federal safety standards as all cars. Importantly, it also attained the important benchmark of being certified a zero-emission vehicle (ZEV) by EPA, the ultimate goal for all motor vehicles of the future.

Chevrolet’s Equinox Fuel Cell so impressed Green Car Journal editors at the time that it was recognized with the magazine’s Green Car Vision Award™. This marked the first time the magazine honored a limited production vehicle for its forward-thinking technologies and potential for influencing the future of personal mobility. For a highly advanced developmental hydrogen vehicle tasked with shepherding in an entirely new age of transportation, that’s perhaps the highest praise we could give.

Propel alternative fuel pump.

While there are many reasons why the alternative fuel vehicle field has radically changed in recent years, there’s no greater contributing factor to this tectonic shift than Tesla breaking the EV barrier with electric cars people really wanted. Now, with most other automakers going all-in with advanced electric models of their own, these other alternative fuels get precious little media focus.

Today it’s all about plug-in electric vehicles and hybrids. But why? Did these other alternatives fail, or were they so successful they became mainstream technologies? In short, the answer is that their technology has matured to the point where discussion of these alternative fuels simply generates little attention.

Fueling a vehicle with compressed natural gas.

Their widespread use has also been limited by the lack of a fueling infrastructure. For the most part, electrified vehicles do a better job of meeting greenhouse gas reduction goals than alternative fuels that add CO2 to the atmosphere. Plus, the availability of affordable gasoline and diesel fuel hasn’t helped the case for these fossil fuel alternatives.

Ethanol

There are currently 3,561 E85 ethanol stations in the U.S. As might be expected, the majority of these stations are in Midwest corn growing states since ethanol is largely made from corn in this country. E85, also called flex-fuel, can contain 51% to 83% ethanol and the balance gasoline, depending on location. E85 can only be used in flexible-fuel vehicles (FFVs) that are specially designed to run on gasoline, E85, or any mixture of these two fuels in the same tank. Currently, only about two dozen FFV models are available. Over the past 30 years, automakers fitted a great many models with FFV-capable engines to earn bonus federal fuel efficiency credits at little cost. This did little to actually encourage alternative fuel use, though, since it’s estimated that less than 10 percent of the 21 million FFVs on U.S. highways actually use E85.

Flexible-fuel vehicle illustration.

Most of the gasoline sold in the U.S. contains up to 10 percent ethanol (E10) to mitigate vehicle emissions, with the amount varying by region and season. All automakers approve blends up to E10 in their gasoline vehicles. As of 2011, EPA began allowing the use of E15 (10.5 to 15 percent ethanol) in model year 2001 and newer gasoline vehicles. While the amount of ethanol used per gallon of fuel is minimal, overall ethanol use is significant and growing due to the huge number of gasoline fueled vehicles on the road.

Biodiesel

Far fewer biodiesel stations are available across the country, about 192 at last count. Biodiesel can be used in its pure form (B100) or blended with petroleum diesel fuel. Common blends include B2 (2 percent biodiesel), B5 (5 percent biodiesel), and B20 (20 percent biodiesel). Since most automakers only approve use of blends up to B5 and some up to B20 in their diesel models, and light-duty diesel vehicles are sold in small numbers in the U.S., biodiesel accounts for a small fraction of the country’s fuel use.

Biodiesel pump at station.

One of the big criticisms of biofuels like ethanol and biodiesel is that they require the same resources –water, land, and fertilizer – that are used to grow food. According to researchers at the University of Virginia, about a third of the world’s malnourished population could be fed by using resources now used for biofuel production.

That said, things could be looking up for biofuels. Today there are hundreds of research projects worldwide – and even some near-ready production facilities – aimed at capturing CO2 and converting it into conventional fuels, biofuels, and carbon-based chemicals. This would effectively release agricultural resources to produce needed food rather than fuel. Plus, whether CO2 is converted to conventional fuels or biofuels, the result is the same since this serves to decrease fossil fuel use and reduce CO2 in our atmosphere.

Compressed natural gas Ford F-150 pickup.

Natural Gas and Propane Autogas

Compressed natural gas (CNG), liquefied natural gas (LNG) and liquefied petroleum gas (LPG) are niche fuels used mainly by government and private fleets, many with their own fueling facilities. A limited number of new CNG and LPG light-duty vehicles are available, mostly pickups and vans. There are also companies that specialize in aftermarket conversion of light-duty models to run on CNG and LPG that are suitable for varying fleet uses, from taxis and government vehicles to service trucks and vans. Combined, there are presently some 21 CNG models and 22 LPG models from which to choose.

These fuels are popularly used in heavier vehicles like transit and school buses, trucks, and vocational vehicles. Since these alternative fuel vehicles are typically owned by fleets where operating cost is a driving force in their decision making, it’s possible we may see trending toward electric propulsion in coming years as the cost of electrification comes down and driving range increases. At present, the U.S. Alternative Fuels Data Center estimates there are 884 CNG, 62 LNG, and 2844 LPG stations available for refueling these alternative fuel vehicles.

Commercial van running on propane autogas.

Even amid the frenetic activity and product introductions surrounding electrified vehicles, we know this: Alternative fuels beyond electrons remain in play and will continue offsetting petroleum use in their own way. Some may be suitable for commercial applications but not personal transportation. Others may find success only in niche markets. Still others – depending on further development and commercialization – may fuel vehicles while also achieving important societal objectives like removing carbon from our atmosphere. Plus, of course, there could be new ‘green’ or designer transportation fuels that emerge in the coming years. All this means it could be a fascinating ‘alternative’ road ahead.

Even amid the huge effort now underway to gain market share with new and coming battery electric vehicles, automakers show a continuing interest in keeping the potential of hydrogen vehicles alive. Indeed, the most high-profile players in this space are taking the next steps toward normalizing the way we look at zero-emission hydrogen fuel cell vehicles, models that drive on electricity generated by an electrochemical reaction of hydrogen and oxygen.

One of the advantages of a hydrogen fuel cell vehicle has been its ability to refuel in five minutes and then deliver 300 or more miles of driving range. That’s about the same amount of time it takes to fill a gas tank, an important baseline. Electric vehicle batteries, on the other hand, typically take many hours to charge. Today’s electric vehicle fast-charging, and the potential for newly-developed extreme fast charging (XFC) technology, could diminish the hydrogen fuel cell vehicle’s rapid refueling advantage.

Still, high-profile players in the auto industry like Honda, Hyundai, and Toyota apparently feel strongly that hydrogen fuel cell electric vehicles (FCEVs) may play an important part in our driving future. Honda currently leases the Clarity Fuel Cell sedan to California residents living or working in areas where hydrogen fueling stations are available. Hyundai also offers its NEXO hydrogen fuel cell crossover model and Toyota its Mirai fuel cell sedan. Since there are only 47 hydrogen stations in the U.S. with 42 of these in California, it’s really no surprise that all three automakers focus their fuel cell vehicle sales exclusively to limited areas with hydrogen fueling.

Underscoring hydrogen’s continuing momentum, Toyota will shortly release its second generation Mirai sedan. Introduced five years ago as the first fuel cell model offered for sale to retail customers, Toyota’s current Mirai is as notable for its styling as it is for its advanced zero-emission propulsion. Its swoopy, angular, and stylistically forward design does speak ‘future” – which, by the way, is what ‘Mirai’ actually means in Japanese – but that design has been a bit too much for most folks’ taste. The coming, all-new 2021 Mirai changes all that.

As shown by the new model’s concept, the second-generation Mirai is nicely sculpted with smooth-flowing lines, presenting as a stylish mainstream sedan with coupe-like design influences. Evolving from the front-drive first-generation Mirai, it uses a new rear-drive platform with a more rigid body structure that’s longer, lower, and wider than its predecessor, riding on a 114.9-inch wheelbase and featuring a length of 195.8-inches with a 74.2-inch width.

This new design is accompanied by a reimagined interior that’s more spacious and now allows for five passenger seating rather than four. Its multimedia system includes navigation and dynamic audio provided by a JBL sound system with 14 speakers. The Mirai’s handsomely sculpted dash features a 12.3-inch, high resolution TFT touchscreen. Drivetrain advancements are also part of the package. While full details have not yet been disclosed, the 2021 Mirai is expected to feature a more advanced fuel cell system featuring increased performance and up to 30 percent greater driving range. Like the model before it, the new Mirai is capable of filling up its hydrogen tank in just five minutes.

Beyond light-duty vehicles, where hydrogen could become a major transportation fuel is in over-the-road trucks that travel fixed routes, where hydrogen refueling stations are available. While adding larger and heavier batteries to increase the range of personal-use electric vehicles is not a big problem, every pound of battery capacity added to increase the range of commercial trucks means a pound less of payload, impacting the bottom line. Thus, fuel cells could prove to have a large advantage over electric trucks and be appealing in the commercial world.

While adding larger and heavier batteries to increase the range of personal-use electric vehicles is not a big problem, every pound of battery capacity added to increase the range of commercial trucks means a pound less of payload, impacting the bottom line. Thus, fuel cells could prove to have a large advantage over electric trucks and be appealing in the commercial world.

Supporting this notion is Anheuser-Busch, which has ordered up to 800 Nikola Two hydrogen fuel cell semi-tractor trucks for its operations. Two prototypes are already delivering Budweiser beer. On another front, Hyundai and big-rig producer Cummins may jointly develop and commercialize fuel cell powertrains by combining Hyundai’s fuel cell systems with Cummins’ electric powertrain, battery, and control technologies. Toyota and Kenworth are building 10 fuel cell semi tractors for use in and around the Port of Los Angeles and Port Heuneme, California, where decreasing port-related emissions is a significant challenge.

Where is this all leading? Toward the future, of course…one that continues to evolve with an as-yet unknown mix of conventional, electrified, and alternative fuel vehicles being developed by legacy and newly-launched auto and truck manufacturers. Each has its own vision of what our driving future will look like. Time will tell what role hydrogen will play in this unfolding transportation world.

Hyundai, part of a very exclusive club offering hydrogen fuel cell vehicles in the U.S., has followed its initial Tucson FCEV with the all-new Nexo. It’s available only in California where hydrogen fueling opportunities, while limited, exist in greater numbers compared to other states.

The Nexo represents a step forward for FCEVs in that Hyundai is selling the 5-passenger hatchback and not just leasing it, as is typically the case with hydrogen vehicles. It also uses a purpose-built platform rather than being based on an existing model like the Tucson FCEV.

As a hydrogen fuel cell vehicle, the Nexo’s fuel cell takes in hydrogen and oxygen to create electricity for powering an electric motor, with zero emissions. The heart of the Nexo is its 95-kW proton-exchange membrane fuel cell stack and 1.6-kWh lithium-ion battery pack. These supply electricity to a 161-horsepower, 291 lb-ft AC induction motor located beneath the hood. Power is transferred to the road through a single-speed, direct-drive gearbox. Hydrogen is stored in three 10,000 psi tanks with a total capacity of 156 liters, delivering an EPA estimated driving range up to 380 miles.

Hyundai reduced the size and weight of the fuel cell compared to that used in the earlier Tucson FCEV. The new fuel cell uses only 56 grams of expensive platinum rather than the Tucson’s 78 grams. Hyundai also improved cold-weather performance so the fuel cell starts in temperatures as low as -22 degrees F. Like the Tucson and other fuel cell vehicles, refueling with hydrogen can be done in as little as five minutes.

There was never a doubt that Honda could achieve its goal in developing a production fuel cell vehicle powered by hydrogen. This automaker already proved it could build and sell another gaseous fuel model – the Civic Natural Gas – that ran as seamlessly as a more conventional gasoline-powered Civic. Hydrogen is just another fuel in gaseous form, right?

Ah, but hydrogen. This zero-emission fuel is more of a challenge since hydrogen wouldn’t be used in an internal combustion Honda engine, but rather in a fuel cell powerplant to electrochemically create electricity, without combustion or emissions. This electricity would provide energy to power electric motors, no differently than in a battery electric vehicle. Make no mistake that this is a very advanced powertrain technology…a future technology, aimed at today.

This image has an empty alt attribute; its file name is Honda-Clarity-Fuel-Cell-Cabin-1024x576.jpgThere have been many developmental milestones along the way. The Honda FCX developmental vehicle we drove at Sears Point Raceway in 2003 offered proof that Honda was up to the challenge. Testing the FCX Clarity Concept at Laguna Seca Raceway in 2006 showed how quickly Honda’s fuel cell vehicle development could progress in a short time.

The all-new 2017 Clarity Fuel Cell is the finished product, currently available in California at a $369 per month lease that includes up to $15,000 of hydrogen fuel. It features an aerodynamic and stylish design nuanced with futuristic touches like angled rear wheel side skirts and eye-catching LED exterior lighting, combined with a pleasing cabin and significant on-board tech.

This image has an empty alt attribute; its file name is Honda-Clarity-Fuel-Cell-Underhood-1024x576.jpgClarity Fuel Cell's new fuel cell powertrain is substantially evolved from earlier iterations and offers an impressive 366 mile driving range. Importantly, Clarity Fuel Cell delivers satisfying driving dynamics that made us smile during our recent seat time on twisty roads and highways on California’s Central Coast.

Apparently, the future has arrived.

We’ve been intrigued by Honda’s Civic natural gas program since this vehicle began serial production at the automaker’s Ohio assembly plant in 1998.

It is a pretty amazing car, built alongside its conventionally powered cousins on the same line, but with the unique components that enable it to operate on clean compressed natural gas (CNG) – a high-compression engine with hardened valves and other natural gas- specific hardware, special lines and fittings, a pressure vessel instead of a gas tank, and so on. It may be equipped with different components, but in the end the natural gas variant drives like the gasoline Civics that leave the plant.

This is a good thing since ‘transparency’ is important. While most drivers may want environmentally-conscious vehicles, they tend to also want ones that are familiar in most ways. The 2012 Honda Civic Natural Gas  – Green Car Journal’s 2012 Green Car of the Year –has been showing us how well Honda has accomplished this job since it began operating as part of our long-term test fleet in 2012.

The natural gas variant’s 1.8-liter engine delivers 110 horsepower – 30 less horsepower than the gasoline version – although the difference isn’t really noticeable during the daily drive. The thousands of miles we’ve now spent behind the wheel bear this out.

The CNG version Civic is not only mainstream-stylish and comfortable, it’s also fuel efficient. We averaged better than 36 highway mpg on a recent tank with another tank in city driving averaging 26 mpg. This was done in ECON mode, with Honda’s ECO Assist system engaged to modify engine operation and other power-using systems to increase driving efficiency. Our combined mpg readings have been averaging 30.8 mpg combined fuel economy, right where it should be considering EPA’s 31 mpg combined estimate.

We've found that engaging the ECON function helps mpg but does diminish throttle response, so entering interstates may be best done with ECON off. With ECON on or off, though, the Civic Natural Gas provides the kind of solid driving experience we can appreciate.

Honda mounts the Civic’s 3600 psi tank between the rear wheels, a position that also places it partially in the rear of the trunk behind a finished panel, resulting in a substantially smaller trunk volume than conventional Civics. The tank holds the equivalent of about eight gallons of gasoline, depending on ambient temperatures during refueling since temperature can influence fill volume. Our range at fill-ups typically shows about 220 to 240 miles on the car’s distance-to-empty gauge.

The Civic Natural Gas test car we’re driving offers an array of welcome features including Honda’s navigation system, which bumps the price up $1,500 from this model’s base MSRP of $26,155 to $27,655.

The Mercedes-Benz G-Class, or G-wagen – short for Geländewagen – has been around since 1979. It looks like Mercedes-Benz could be offering this iconic, off-road capable SUV for many more years.

Mercedes-Benz Advanced Design Studio in Carlsbad, California created the Ener-G-Force concept shown at the 2012 L.A. Auto Show, a civilian version of the Mercedes-Benz entry in the 2012 Los Angeles Design Challenge. Mercedes-Benz was one of six entrants that presented their vision of the Highway Patrol Vehicle 2025, this year’s theme.

The futuristic Ener-G-Force is powered by hydrogen fuel cells supplying electricity to four wheel-hub motors that motivate 20-inch wheels. Advanced electronics adapts power output for each individual wheel to provide precisely the right amount of traction required for the respective terrain. A roof-mounted, 360-degree ‘Terra-Scan’ topography scanner provides a handy read on nearby surroundings, with scan results used to adjust the spring and damping rates as well as other suspension parameters for maximum on- and off-road traction.

Recycled water stored in tanks on the Ener-G-Force roof is transferred to an on-board hydro-tech converter, which in turn electrolyzes water into hydrogen for the fuel cells. This renewable energy could provide an estimated zero-emission operating range of about 500 miles.

The vehicle’s strikingly-styled side skirts are designed to house either energy storage units or hot-swappable battery packs. Color changes in the side skirts’ illumination indicate energy pack operating and charge status.

The police version is differentiated with emergency lights integrated into the roof and other law enforcement equipment and markings. Less glass area is also found on the police variant to provide a safer environment cocoon for police officers.