Wednesday, April 2, 2008

Diesel vs. Hybrid

In several posts I have advocated diesel as a better alternative to hybrid cars. At the risk of being accused of posting another BMW advertisement, here is news which tends to vindicate my position. The Sunday Times of London did a test comparing a Prius with a BMW 520d. The 520d has the regenerative braking system described last Wednesday in relation to the 118d, but is a substantially larger car.

The test comprised a 460-mile drive from London to Geneva, combined with 100 miles of city driving. The BMW won by 41.9 miles per (US) gallon, compared to the Prius at 40.1 mpg. By American standards, this test may seem biased towards long-distance freeway motoring, which would favor the diesel. (In Europe, cars are used less around town because there is good public transport but are more often used as an alternative to short-haul flights.) It should also be noted that a gallon of diesel both costs more and produces slightly more greenhouse gases per gallon burnt. Even so, this is an impressive result. The 5-series is after all the second-largest car in the BMW range, and 500 pounds heavier than the Prius. The BMW driver also reportedly used the radio and A/C while cruising at 75, whereas the Prius driver eschewed these luxuries to save energy. The 118d would surely have been quite a lot more economical.

4 comments:

FixedXorBroken said...

Another BMW ad eh?

Tony Welsh said...

More of a diesel ad I would say. Note that I have extolled the virtues of Audi and Mercedes diesels as well, and look forward to being able to do the same for other companies -- especially when they are avaiilable in the US.

Tate said...

How is the overall environmental impact? What I mean is materials used to build both, and to reclaim. I have not seen a "lifetime" environmental impact. I guess, and that's all it is, that the Hybrid may have a worse effect due to it's large chemically charged batteries, and hire percentage of plastics used va a diesel. Any information?

Tony Welsh said...

I do not know the numbers, but I think it is right to be skeptical about hybrids. In the short term my guess is that diesel is the way to go, but not a final answer. Hybrids are at least pioneering electric technology which, together with clean power sources replacing coal, might be the long term solution. (Though hydrogen may be the better bet, again together with clean power generation.)