| | | Monday March 17, 2008 | 
Is this a case of man bites dog? A mid-size BMW sedan equipped with a diesel engine returned better fuel economy on a 545-mile, London-to-Geneva, run than a gasoline-powered Toyota Prius. A BMW 520d with a 2.0-liter diesel engine and regenerative braking (but no heavy duty hybrid features) got 41.9 mpg while the full-hybrid Prius, 500 pounds lighter, got 40.1 mpg.
Two writers for the Sunday Times (London) wondered if official mpg ratings were accurate after hearing from their readers who said the Prius ratings were high by 15 (U.K.) mpg. "If our readers are right and the official figure is wrong it has important implications, not least of which is that people driving frugal diesels are getting a raw deal," the paper said, since hybrids get some tax and roadway access benefits in Europe as they do in the U.S. To find out, they drove BMW's midsize 5 Series sedan and the Prius London-to-Geneva, adding 100 miles to the route "to give the Prius the advantage of running in urban conditions where its petrol-electric drivetrain comes into its own." Whilst the BMW "doesn't have the external look of a green car and you don't get the same self-righteous glow when you are driving it," it does have a series of energy-saving features BMW calls EfficientDynamics: battery recharge when braking, good aerodynamics, low rolling resistance, a continuous fuel consumption gauge on the dashboard, and a six-speed manual transmission that is rated as improving fuel economy by about 10%. Testers found the 520d "not startlingly quick ... [but] it cruised happily at the French autoroute limit (dry conditions) of 78mph towards the champagne region." When the trip was done, the BMW still had a third of its tank in reserve. The Prius, in comparison, ran out of gas. Not because of lousy mileage but because the tank is smaller (and the testers had a spare can of gas aboard). Acceleration was "hardly dragstrip quick and slower than the BMW, but still respectable." The Prius weighed 573 pounds less and had an aerodynamic shape "as slippery as a campaign manager discussing political donations," leading the testers to believe "the Prius should take less energy than the BMW to maintain a constant cruising speed." Not so. As many people know, the advantage of hybrids lies in urban driving where the stop-and-go recaptures the car's energy. On the highway, it's one more four-cylinder car pushing throught the wind.
The full story is on the website of the Sunday Times (London): "Toyota Prius proves a gas guzzler in a race with the BMW 520d: The Toyota hybrid is hailed as an eco-paragon, so how does it fare against a big BMW? To find out our correspondents go on a run to Geneva." An Imperial gallon is 1.2 U.S. gallons, or a U.S. gallon is 0.83 Imperial gallons. Roughly speaking, discount the Times numbers by one-fifth: a 50 mpg vehicle to them is a 40 mpg vehicle to us Yanks. Another reason we should all go metric. Posted By: Bill Howard | | | | | | Posted by: Jimmy Le
March 18, 2008 11:20 AM 40 mpg for the prius? I have never been able to acheive any thing less than 50 mpg. This test in unscientific at best, you have two different drivers whose driving habits can be vastly different. On my prius, I average 55 mpg while my wife averages 48 mpg. Posted by: RedM3
March 18, 2008 3:44 PM Don't get your panties all twisted there Jimmy. If you read the story it details that on the highway the Prius is just another 4 cylinder pushing through the wind. I think that might suggest not everyone will get the full benefit of a hybrid depending on their driving habits. Good to know if you're a sales person who travels a lot of highway miles. Posted by: Alen
March 18, 2008 4:26 PM The Prius advantage is only in the City plus, driving below the 40 MPH. If you go above the 40MPH, you're just another car on the car. It isn't a green vehicle anymore, just another 4 cylinder air polluter. And given that most people in the US tend to travel some distance on the highway to and from work the Prius isn't as Pious as many of it's owners make it out to be - it would have been interesting to test it against something like a Jetta turbodiesel and see what that did. Posted by: RedM3
March 18, 2008 5:23 PM Good point Paul. I think Biodiesel is an excellent alternative fuel. Better than electric. It's clean burning, produced domestically, contains no petrolium, and renewable. Just take the fat from my Ribeye (or oil from soybeans for the animal lovers) and convert it to a nontoxic renewable energy source. What's not to love? Posted by: WarnerYoung
March 18, 2008 5:55 PM Even driving on the highway at 65 to 70 mph, I generally average 45mpg (US) in my Prius. I'd be curious to know what kind of driving style they used in these tests. It's quite possible to drive a Prius badly and get bad gas mileage. To be fair, it's possible the same was true of the BMW. Posted by: Alan
March 18, 2008 10:54 PM The article stated 78 mph. Prius's 76 HP gas engine must be pushing very hard at that speed, hence use more gas. BMW 520d's 136 HP engine won't be working as hard as the Prius. | | | |
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