Green Car Journal editors previously experienced 10,000 miles of driving in BMW’s i3, with those miles behind the wheel of a 2015 i3 REx several years ago. We were convinced then, as we are now, that BMW’s i3 is an indispensable, right-sized urban car that’s not only super-efficient to drive around crowded city environs but loads of fun as well.
Chalk that up to its easy maneuverability, great handling, and lightweight construction using a carbon fiber reinforced plastic (CFRP) body over an aluminum and CFRP passenger cell. Plus, of course, there’s the instant torque and surprisingly quick launch provided by the i3’s 170 horsepower electric motor. The i3 became our go-to vehicle for everyday drives.
Now, two years later, we’re 7,500 miles into a long-term test of a 2017 BMW i3 REx and experiencing even more satisfying results. While driving range in the earlier i3 was limited to 81 miles on the model’s 22 kWh lithium-ion battery pack, or 72 miles on batteries with an overall range of 150 miles using electricity from its REx gasoline engine-generator, those numbers substantially increased in the 2017 model year i3 we’ve been driving.
We knew from the start that BMW hit upon something extraordinary with its range-extended REx i3 variant. Simply, BMW recognized that range is a big issue with drivers considering an electric vehicle, and while the i3’s electric range is suitable for a great many drivers, the confidence of extending range with a small engine-generator is real. With the REx variant, most driving can be done exclusively on battery power for convenient, efficient, and zero-emission transport. Occasional trips beyond the i3’s battery range are possible with electricity produced by the REx system.
While a 22 kWh battery pack still powers the 2017 base model, BMW reengineered the 2017 i3 with an optionally available 94 kWh battery pack for greater battery electric range, plus an available REx variant with a slightly larger 2.4 gallon gas tank. The result is notable. The 2017 i3 with the larger battery offers an EPA estimated 114 miles on battery power. Opting for the 2017 i3 REx variant delivers an EPA estimated 97 miles of battery range (somewhat less than the electric-only model due to the REx system’s additional weight), and 180 miles of overall driving with the range extender.
We did find that the shorter 72 mile battery range of our 2015 i3 REx found us using the range extender somewhat regularly. With the longer 97 mile range we’ve only been into the range extender a few times, other than those times the range extender was required to automatically run for service since we hadn't been using it. Yes, it’s only a difference of 15 additional battery electric miles, but with our everyday routes and driving habits those additional miles have made a difference.
The i3 is a kick to drive and we tend to smile a lot as our off-the-line acceleration regularly surprises others between traffic lights. The twin displays offer easy-to-reference information and controls are intuitive. For such a small car, the i3 provides a surprising amount of headroom and overall passenger comfort. The trunk is small but adequate for our everyday needs. Charging with our wall-mounted 240-volt charger is a breeze. It's also economical since we set the i3 to charge at off-peak times and enjoy a discounted electric vehicle rate from our local electric utility.
Green Car Journal editors continue to find our 2017 BMW i3 tester a favored go-to vehicle for daily drives because it’s fun and easy to drive in addition to being clean and economical. We expect that will continue to be the case in the months ahead because it's a combination that’s just hard to beat.
The BMW i8, the second milestone model to emerge as part of BMW’s innovative ‘i’ sub-brand, earned the distinction as Green Car Journal’s 2015 Luxury Green Car of the Year™ at the recent Washington Auto Show in the nation’s capital. There are compelling reasons for this.
BMW’s flagship i8 not only breaks new ground in defining how a high performance vehicle can achieve environmental goals, but it does so in ways that do not impose limitations on the driving experience. Importantly, this car fits BMW's ‘Ultimate Driving Machine’ image while providing levels of environmental performance increasingly appealing to those buying aspirational vehicles.
BMW i8 LIFEDRIVE ARCHITECTURE
Beneath its stunning, gull-winged body is BMW’s innovative LifeDrive modular architecture. The Life module is essentially the i8's 2+2 passenger compartment constructed primarily of strong and lightweight carbon fiber-reinforced plastic (CFRP), created with carbon fiber manufactured at a dedicated SGL Automotive Carbon Fibers LLC facility in the State of Washington. The result of a joint venture between SGL Group and BMW Group, this manufacturing plant strengthens the i8’s environmental credentials further by producing carbon fiber using renewable hydroelectric energy.
The i8’s aluminum Drive module contains the gasoline engine, lithium-ion battery pack, electric motor, and associated electronic components. It uses a 228 horsepower, 1.5-liter turbocharged three-cylinder engine to power the rear wheels through a six-speed direct shift transmission. Front wheels are driven by a 129 horsepower electric motor and two-stage automatic gearbox. Energy is supplied by a 7.1-kilowatt-hour lithium-ion battery pack located within a tunnel between the two front seats. It can be fully charged in just an hour and a half.
Power can be provided solely by the electric motor for about 22 miles of zero-emission driving at speeds up to 75 mph. Together, the rear-mounted engine and front electric motor deliver all-wheel drive performance with a combined maximum power of 357 horsepower and 420 lb-ft of torque. Drivers are afforded the latest in advanced on-board electronics and safety systems expected in this class of vehicle.
Driving the i8 at speed provides a clear understanding of just what BMW has accomplished with its lightweight, high-tech luxury sports coupe. Green Car Journal editors found the i8’s handling superb and performance exhilarating. BMW’s Driving Dynamics Control allows choices of eDRIVE, ECO PRO, SPORT, and COMFORT drive settings. In Sport mode, the i8 can accelerate from zero to 60 mph in 4.4 seconds and deliver a top speed of 155 mph. Driving range is 310 miles under normal driving conditions. Engine overrun and regenerative braking are used to charge the battery pack and a start-stop feature helps conserve energy.
The BMW i8 blends thrilling performance, innovative design, and environmental achievement in an exceptional luxury sports coupe, while offering a combined EPA city/highway battery electric efficiency rating of 76 MPGe (miles-per-gallon equivalent). Its DNA is 'green' by nature and design, making it a natural selection for 2015 Luxury Green Car of the Year™.
Illuminating the road ahead is a crucial element in driving. It’s also one that has long benefitted from technological innovation. To this end, Audi celebrates the evolution of automotive lighting with its Sport quattro laserlight concept car. The high performance, two-door, Plasma Red coupe harkens back to the iconic 1983 Sport quattro even as it’s abundant advanced technology and design cues point to the future.
The laserlight concept is named for its future lighting technologies. Two low-profile trapezoidal elements are visible within the headlights. An outer one generates low beam light using matrix LEDs and an aperture mask, while an inner element produces laser light for the high-beam.
Laser diodes are significantly smaller than LED diodes, only a few microns in diameter. They can illuminate the road for a distance of nearly 1,640 feet, approximately twice the lighting range with three times the luminosity of LED high beam lights. This technology is finding use in the 2014 R18 e-tron quattro for track duty.
Motivating the laserlight concept is a 4.0-liter, bi-turbo V-8 TSFI (turbo stratified fuel injection) engine and a disc-shaped electric motor located between the engine and transmission. The V-8 produces 560 horsepower and 516 pound-feet torque, with the electric motor contributing an additional 148 horsepower and 295 pound-feet torque. A modified eight-speed Tiptronic transmission is mated to the quattro drivetrain with a sport differential at the rear axle.
Electrical energy is stored in a 14.1 kilowatt-hour lithium-ion battery, sufficient for 31 miles of all-electric driving. When the V-8 and electric motor are working together, the Audi Sport quattro laserlight concept can accelerates from 0 to 62 mph in 3.7 seconds. Top speed is 189 mph. This impressive performance comes with an equally impressive 94 US mpg fuel economy. This is achieved in part through its electric plug-in operation in addition to a cylinder on demand system that deactivates four cylinders of the V-8 under partial load. Also helping is a start-stop system and several levels of regen braking to enhance driving dynamics.
Drivers can switch between three different modes. In EV mode, just the electric motor operates with sufficient high torque power, even outside the city. The active accelerator pedal indicates the transition by a change in pedal resistance so a driver can intentionally influence the mode selection. The Hybrid mode provides optimal interplay between the V-8 and the electric motor for best fuel-savings, and additionally incorporates environmental and route data. A driver can choose the Hold and Charge modes to ensure sufficient electrical energy is available for electric-only driving at their destination. There are different levels of regenerative braking to enhance the driving experience.
The laserlight’s multifunction sport steering wheel has buttons to control the hybrid drive, start-stop function, vehicle handling system, and the car’s virtual cockpit. Key information is shown on the large Audi TFT display in high-resolution 3D graphics. A cutting-edge Nvidia Tegra 30 processor handles the graphics.
Nearly all functions can be controlled from the further-developed MMI mounted on the center console. Its large rotary pushbutton, which also serves as a touchpad, can be pushed in four directions. It’s surrounded on three sides by four buttons that control the main menu, submenus, options, and a back function. The intuitive layout is similar to a smart phone with all frequently used functions accessed lightning fast.
Lightweight design plays a major role in the Audi laserlight concept’s dynamic performance. A combination of ultra high-strength steel sheet and structural elements of cast aluminum is used in the occupant cell. The doors and fenders are made of aluminum, with the roof, engine hood, and rear hatch and other components made of carbon fiber reinforced plastic (CFRP). Thus, the concept weighs 4,079 pounds including the weight of the large battery pack.
Race car designers go to extreme measures to make competition vehicles as light as possible. Lighter is faster. It’s simple physics; less horsepower is required to accelerate a light vehicle compared to a heavy one. So on a given amount of horsepower, a lighter race car with advanced materials will be faster than one that weighs even a few pounds more. It also takes less energy to slow the car, providing better braking performance. The use of lighter and more advanced materials generally contributes to better handling, too, since there is less mass working on the chassis through the corners.
Lighter vehicles are also more environmentally friendly since they require less energy to move from point A to point B. Shaving a few hundred pounds off a car design can yield major improvements in fuel economy. In addition to improved mileage, electric vehicles will see longer range between charges if they can be made lighter.
Trimming pounds off a production car is not as easy as it seems, however. Today’s road worthy vehicles must feature hundreds of pounds of federally mandated safety equipment that wasn’t required or available a few decades ago. Equipment like antilock brake systems, multiple airbags, advanced computer controls, and crash mitigating high-strength body structures all add weight to a vehicle design. Pile on the comfort and convenience equipment that most new car buyers expect in a modern car or light truck and the extra bulk adds up fast.
That’s why vehicle designs like the new BMW i3 and i8 are so intriguing. These models are revolutionary for mass production vehicles, featuring clean sheet designs that found BMW designers throwing traditional materials and production methods out the window, resulting in lightweight electric-drive cars with maximum strength for safety.
For example, the i3’s primary body and chassis structure are composed of two separate units that form what BMW calls the LifeDrive architecture. The primary body structure is the Life module and the Drive module incorporates the powertrain components. The passenger cell module is made from Carbon Fiber Reinforced Plastic, or CFRP. This is the first ever use of CFRP in a mass production vehicle. Carbon Fiber Reinforced Plastic is every bit as strong as steel yet is 50 percent lighter. When you can trim half the weight off something as large as a body structure, you are talking major weight savings.
Aluminum has been used as a lightweight material in the transportation industry for many years. The i3’s rear Drive module that houses the electric drive motor, rear suspension, and optional range extending gasoline engine is made of aluminum. While both are light and strong, Carbon Fiber Reinforced Plastic is even 30 percent lighter than aluminum. Materials throughout the i3 were selected for their weight saving properties and for their sustainability characteristics.
Beneath the flat floor (there is no transmission tunnel) of the i3 is a space-saving 22-kWh lithium-ion battery pack that tips the scales at 450 pounds. Power is delivered by a hybrid synchronous electric motor. The motor produces 170 horsepower with 184 lb-ft torque and can spin up to 11,400 rpm. The compact electric motor offers immediate torque and weighs just 110 pounds. With a curb weight of just 2,700 pounds, the i3 is nimble and great fun to drive. As in racing, automakers strive to save weight because it gives them a competitive edge. Sometimes, less is more.