Will Cars Shrink With New Mileage Rules?

Yesterday's announcement of new fuel mileage and car emissions rules has riled up all kinds of special-interest groups. Some safety advocates suggest that these new rules will lead to smaller cars. The smaller the car, the less safe it is, most experts agree. We've already detailed why, and it comes down to simple physics.

Looking at these new regulations, it is possible that smaller vehicles may be one result of the increased mileage rules. The most radical changes, however, may not impact cars of any size.

The stringent new rules call for an average truck rating of 30 mpg. That means truck-based SUVs especially will see radical changes. For the 2008 model year, Ford's light trucks just beat the CAFE average, coming in at 24.7 mpg. CAFE now is set at 23.1 mpg. Models like the Chevy Suburban and Ford Expedition may become extinct. The Ford Explorer is already moving to a car-based crossover, and GM may have to pull the plug on its slow-selling Chevy Tahoe, GMC Yukon and Cadillac Escalade.

Hummer is in the process of being sold, and its hulking H2 sells so few units a month it's unlikely you've seen a new one in your town in a year or more.

Where does that leave cars? Much safer once there are fewer two-ton SUVs entering the driving pool. Plus, many of the most efficient cars today aren't even the smallest. The Toyota Prius, Toyota Corolla, Honda Civic, Chevy Cobalt, Ford Focus, VW Jetta TDI and Ford Fusion Hybrid are relatively large compacts or midsize vehicles, and they all get similar or better mileage than a Toyota Yaris or Honda Fit. Only the very small Smart ForTwo stands out as something that consumers and safety advocates would consider "too small." Plus, the best-selling cars remain compact and midsize cars.

 It's likely the most fuel-efficient engines in the future will continue to be put into these compact and midsize cars because the cost is more easily absorbed versus entry-level subcompacts.

With another five years before these new rules go into full effect and the resulting new cars and engines are likely to be introduced, it seems much too early to guess at safety ramifications.

Safety could suffer if we boost mileage by making cars smaller (USA Today)  

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