Wednesday, March 26, 2008

Green BMW

The BMW 1-series was introduced to the USA recently with 3-liter 6-cylinder engines. Unfortunately we will not get the diesel model, the 118d. As its name suggests, this is powered by a 1.8 liter diesel engine, producing 141 horsepower and 221 pound feet of torque. This is enough to propel it to 60 in 8.8 seconds, which is not exactly blisteringly fast but is fast enough for most people, and a lot better than a Prius. It was also enough to win the World Green Car of the Year award in New York this week.

The car also boasts what BMW calls Efficient Dynamics, which as far as I can ascertain comprises regenerative braking and automatic stop/start. The latter works by switching the engine off when the car is stationary and put in neutral. It restarts when the clutch is disengaged. The regenerative braking is more problematic; the regained energy is used to charge the battery, but since -- unlike a hybrid -- there is no electric motor this can ultimately be used only for the car’s electrical systems. (Which include electric power steering, by the way.) It does however reduce the demands on the alternator, which disengages when the battery is charged thus reducing the drag on the engine. I would have thought the contribution of that feature towards fuel efficiency would be small, but every little helps. And you certainly cannot argue with the overall result. The car is rated at 59mpg on the highway. (An independent test by the German magazine AutoZeitung achieved 47.9 mpg in mixed driving, compared to 39.8 for a Toyota Prius.)

My only concern was that they use low-rolling-resistance tires to squeeze a few extra miles per gallon out of the car. Such tires normally mean low grip, but in this case it seems my concern is misplaced. British magazine Autocar reports great handling and stellar braking performance; 155 feet from 70mph, which is about as good as it gets.

6 comments:

FixedXorBroken said...

Is this Tony's pro-Climate Change Blog? What's with the car ad?

Tony Welsh said...

Wish it was an ad; that would mean I got paid for it, which I didn't. Wednesdays I normally talk about cars, which make a significant contribution towards greenhouse gas emissions. A car which does 50mpg seems like a worthy subject, even though it will not be made available in the US.

E.M. said...

My father is a flooring subcontractor and he drives the standard white, F150. The Pig, as it is affectionately known, eats 60 gallons and 500 miles a week, so a new truck is needed in the next couple years. He's holding out for a diesel half ton, but it seems the wait isn't getting any shorter. Have you heard anything about diesel pickups?

Tony Welsh said...

All three US manufacturers offer diesel engines in their 1-ton trucks but not their 1/2 ton trucks. This is due to change however, with Ford F150 being the first to offer diesel in 2009. See http://www.fordf150.net/diesel/

RosInSheffield said...

Just a quickie - when you quote fuel consumption in mpg, are the gallons US or Imperial?

Ros

Tony Welsh said...

The 59 mpg is from the US EPA (Environment Protection Agency) and is in miles per US gallon. The German magazine results were originally quoted in litres per 100 km, and converted to miles per US gallon. I try to always use US gallons.