Since the Arab Oil Embargo of the mid-1970s, automakers and government officials have been on a quest to boost fuel efficiency. The gains have come slowly, but today's average unadjusted fuel economy for passenger cars sold is 29.8 mpg, up from a Corporate Average Fuel Economy target of 18.0 mpg in 1978.
Up to now, the improvements have mostly been a direct result of smaller engines. But there's more to come. Next-generation autos will benefit from the use of lightweight body panels, less wiring, and a host of up-and-coming engine technologies, including direct injection, variable valve timing, and cylinder deactivation.
We've collected photos of some of the most promising technologies. From turbochargers and electric motors, to motor-generators and air conditioning compressors, we present some of the best fuel-sipping innovations.
Click on the VW XL1 to start the slideshow, which continues on Design News.
Theoretically, the plug-in hybrid can achieve extraordinary fuel-efficiency numbers, given the proper driving schedule. Volkswagen's proposed XL1 is one such vehicle, reaching 261 mpg, the automaker says. To accomplish that, the XL1 employs just about every imaginable fuel-efficiency technology, including a 47-HP turbo-diesel engine, a 27-HP electric motor, carbon fiber-reinforced plastics in its monocoque, body panels, and anti-roll bars. The brakes also use carbon fiber ceramics, while the engine crankcase, steering gear housing, dampers, and other suspension components are made from aluminum. Even the XL1's windows were designed with weight reduction in mind, all of them being made from polycarbonate.