Can plastic wheels improve fuel efficiency?

Soon, drivers of the new 2015 Audi A8 will have a chance to find out.

The refreshed version of Audi's flagship sedan will be offered with wheels made from a composite material called Chromtec.

The wheel manufacturer, Lacks Wheel Trim Systems, says the wheel comprises "a lightweight structural backbone and a design surface that consists of a proprietary high-impact modified polymer, proprietary urethane cellular foam system and true metallic finishes."

The new material, it says, will save roughly 38.8 pounds per vehicle--a substantial amount even on a large luxury sedan like the Audi A8.

2015 Audi A8 / S8 - 2013 Frankfurt Motor Show

2015 Audi A8 / S8 - 2013 Frankfurt Motor Show

Reducing weight typically leads to an improvement in fuel economy, and on a sedan as big as the A8, any weight savings is a significant achievement.

Since the wheels have a metallic finish, they should be hard to distinguish from conventional alloy rims.

Composite wheels have been tested before: In 2007, the Fraunhofer-Gesellschaft research facility tested wheels made from glass-reinforced plastic (GRP) in its own simulator.

However, the 2015 A8 should be the first production car to have them.

Unveiled last month at the 2013 Frankfurt Auto Show, it's a refreshed version of the current generation of Audi's full-size luxury sedan.

Among the A8 models expected to return for the 2015 model year is the TDI diesel. The new A8 is also expected to keep the 2014 model's 3.0-liter V-6, which produces 240 horsepower and 406 pound-feet of torque.

Whether composite wheels will improve the 2014 model's EPA fuel economy rating--28 mpg combined (24 mpg city, 36 mpg highway)--remains to be seen.

Gas-mileage ratings will be issued several months from now, closer to the time that the new A8 goes on sale.


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