In an effort to sweeten the incentive for those taking advantage of the government's Car Allowance Rebate System (a.k.a. "Cash-for-Clunkers"), Nissan has reportedly sent its engineers back to the lab in order to pinch every last mile out of each gallon of fuel. As it is written, the program offers a sweeter incentive when consumers purchase vehicles with greater efficiency (based on the difference in fuel economy between the purchased vehicle and the trade-in).
Putting the squeeze on the Sentra's four-cylinder powerplant yielded a 1 mpg improvement – not bad for some minor drivetrain tuning. If the EPA reviews and confirms the bump, the small gain may create the necessary 10-mpg difference Nissan's customers need for the top $4,500 credit.
The program is set to expire this November. That isn't enough time for Nissan, or any automaker for that matter, to make drastic changes. However, engineers are able to focus on quicker fixes such as using lightweight wheels, subtle engine tuning, and changing option packages to reduce weight. According to Nissan, the lure of trade-in bonuses to attract new customers has promoted the automaker to divert much of its engineering to the cause.