Carmakers have employed a number of methods to improve the fuel-economy of their cars in the recent past, most notably turbocharging smaller engines and reducing weight. However, the battle to improve mileage and efficiency for cars is stepping up in view of impending CAFE requirements and general market demands, and now engineers are turning to the finer aspects of vehicle design - including reducing friction in the engine, improving gearboxes, and even using thinner electrical wiring to weed out as much performance as they can from cars.

Speaking with Automotive News, an executive from the Hella Corporate Center, Roland Franz, explained that "there's no one big way to save energy," and that we must now look "at ways to save a little here and there."

Friction has long been an enemy of the engineer, due to the detrimental effects such as lost power, reduced efficiency and higher fuel usage. Nowadays, manufacturers are taking notice of friction, and companies such as Nissan and Honda are hard at work to cut it by even the smallest amounts - one example given by Nissan involved slightly changing the angle between the connecting rod and piston in its 2007 HR engine to reduce the side load on the piston as it moved through the cylinder. Meanwhile, Honda and other companies are also working on reducing friction through new innovations, such as the use of polishing tape between parts to increase smoothness.

Engineers are also turning towards gearboxes to improve fuel economy, and reportedly GM is keen to make six-speed transmissions their primary gearbox option due to the 5% fuel economy improvement they show over current four-speed units. Large scale gearbox manufacturers, such as ZF, are already releasing eight-speed gearboxes that show similar gains over six-speed units, however this technology still remains expensive.

But engine improvements and gearbox tweaking are just the tip of the iceberg when it comes to improving the efficiency of our cars. Manufacturers are also looking at the weight of electrical wiring for fuel economy gains - even reducing the thickness of cables by 1/100th of an inch is considered a worthwhile gain, and one company, Lear Corp., is claiming that its products can reduce the weight of electrical systems by about half – enough to shave around 25lb (11.3kg) from the kerb weight of a typical car.