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Consumer Reports rightly ponders specific fuel consumption

I've written in this space on previous occasions about the reality of specific fuel consumption (the amount of fuel needed to produce a given amount of power) in modern cars. While the Corporate Average Fuel Economy standards have remained static for the past two decades, the power output of modern engines has skyrocketed at the same time that mpg numbers have stagnated. When car-makers whine about not being able meet proposed new standards, it simply doesn't ring true because if they can make so much more power from the same amount of fuel, they can surely make the same amount of power they used to make from less fuel.

Consumer Reports noted this after attending a preview of the 2008 Mazda CX-9 which gets a bump in displacement from 3.5L to 3.7L along with 10 hp more than before. This comes with no increase in fuel consumption. When car-makers make upgrades like this one has to wonder if every car-maker needs a compact cross-over like the Rav4 that goes 0-60 in 6.7 seconds. Clearly the answer is no unless the company wants to sell product and as long as consumers keep opting for the vehicle with more power over the lesser model, CAFE standards will be pointless.

New technology like HCCI and small-displacement, direct-injected engines with turbocharging will help improve fuel economy but so far it's mainly been used just to get more power. For 2008, Cadillac is offering a direct-injected version of the 3.6L V-6 in the CTS that bumps power by 40 hp with improved economy compared to the port injected version. Why not offer a smaller 2.8L DI version with the same power and even better efficiency?

[Source: Consumer Reports]

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