Should the EPA Have Changed the BMW 328's Mileage?

When the EPA downgraded the highway mileage estimate for the new BMW 328 to 33 mpg from 36 mpg, it was a big deal. Automakers don't routinely see that kind of change from the agency when releasing a new model. The turbocharged four-cylinder engine — teamed to an eight-speed automatic transmission — is vitally important to the automaker, as it is now the base engine for the company's most popular car.

When a new 2012 328i arrived at HQ for testing, I took it home, loaded my kids in their child-safety seats and headed off for the highway for a bit of an unscientific real-world test. I don't think the EPA got it entirely right this time out.

The destination was an indoor play place that allows two young children a safe haven to exhaust their nearly endless energy. This one is far from our house, 23 miles, but it's a favorite destination, so the ride for the kids — passing the airport and two train yards — wasn't a hardship.

Along with their car seats, I'd estimate that they accounted for an extra 100 pounds or so of weight. The weather was cool but sunny, so I had the air conditioning on at a medium level. Winds were strong, though. Heading north and later south, there were crosswinds and the buffeting was easily felt.

On the trip down and back I maintained a steady clip of around 65 to 70 mph, rarely breaking 70 mph. I did not have the optional Eco mode on, which regulates the HVAC system.

Leaving the highway after 20 miles, the trip computer registered 34 mpg and settled at 34.2 by the time we reached the destination three miles later, driving at a moderate speed with few stops.

On the trip home, the computer displayed 35 mpg about halfway through and topped out at 35.4 mpg; that was the rating displayed as we exited the highway. The few miles more to the house saw that mileage drop quickly to 34.3 mpg.

After 25 more miles of mixed suburban driving later that day and my 23-mile commute to work on Monday in bumper-to-bumper traffic, the computer showed 28.2 mpg. The 328i is rated 23 mpg city and 26 mpg combined.

But it's the highway mileage that is the question. If during my test the 328i couldn't break 35.4 mpg, perhaps the EPA was right to revise the number. But because it reached that number with some serious stress — winds, high speeds, added weight — I'm surprised the EPA didn't rate it higher than 33 mpg.

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