What's the Big Deal With Cars That Get 40 MPG?

| 4/4/2012 11:16:21 AM

Tags: car mpg, fuel efficiency, fuel economy, Todd Kaho,

2012 Honda Fit RedWhy does everyone talk about 40 mpg like it’s some kind of miracle? My beloved Geo Metro got that easily, and that was decades ago. 

Simply put, comparing today’s high-mpg cars with the high-mpg cars of a few decades ago is neither accurate nor fair. Modern cars are much heavier than their predecessors because of federally mandated safety and emissions equipment and consumer-demanded amenities. All of this makes it much more difficult to reach 40 mpg.

If we look back at the first-generation Honda Civic from the mid-1970s, for example, it didn’t have air bags, a catalytic converter or anti-lock brakes. It only weighed 1,500 pounds and could achieve 40 mpg. The smallest car Honda offers in the United States today is the Fit. At 2,496 pounds, the 2012 Fit is 1,000 pounds heavier than the 1973 Civic. The Honda Fit also has a lot of safety equipment that wasn’t around in the 1970s. The body is considerably stronger, and there are six air bags, active head restraints, anti-lock brakes, and a vehicle stability system with traction control.

Automakers are trying to control this weight gain with lighter-weight materials and smarter engineering, but every ounce adds up. Lighter-weight materials are also generally more expensive to produce, so they often don’t fit the budget constraints of a small economical car.

The other factor is that the Environmental Protection Agency (EPA) changed its fuel economy test in 2008 to reflect “real-world” mileage. The testing became more aggressive, with three additional test cycles that included running the air conditioning, harder acceleration and an 80-mph blast. As an example, the 2007 Toyota Prius had a rating of 51 mpg on the highway, 60 mpg in the city and a combined rating of 55 mpg. Under the 2008 test procedures, the same car’s numbers dropped to 45 mpg on the highway, 48 mpg in the city and 46 mpg combined.

The old EPA test procedure needed to be updated, but some think the 2008 change dumbed it down too much and lowers consumer expectations about gas mileage. With a fuel-efficient driving style, I find it easy to regularly exceed the official fuel economy estimates in most new cars. In some, I can beat them by a lot. For example, in a Volkswagen Passat TDI, which uses clean diesel technology and has a highway fuel economy rating of 40 mpg, I averaged 48-plus mpg on an 800-mile round trip. The route was mostly highway driving, much of which was through mountains.

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