Quote:
Originally Posted by brad850csi
Diesel has 15% more energy per litre so it should have at least 15% less consumption. Typically a diesel version of the same car will have a lower diff ratio as well, combined with a more efficient engine design (no spark plugs and higher comp ratio) I'd expect 20-25% difference in fuel consumption would be about right.
Of course a PHEV might be able to match it for the first 100 or even 200 miles but at 500 miles the Diesel will always pull ahead.
|
Add the difference in thermal efficiency between the diesel and gasoline ICE, and the real world findings (*) that a smaller gasoline ICE can even be less fuel efficient than a larger capacity ICE, the diesel will be more fuel efficient cruising any long distance. The smaller gasoline ICE has no chance, when the batteries are discharged and of little assistance in long distance cruising.
We have direct comparisons here in the UK for several model ranges. For example, the 330e (fully charged each night), can never compete for high mileage users, against the diesels of similar performance. The diesel is way ahead on fuel efficiency.
* Here in the UK, many smaller ICE installations have proven to be less efficient when cruising at highway speeds, than the same model with a larger capacity ICE. Total road load can be very similar. To the point manufacturers are questioning/debating the benefits of the smaller, more highly tuned engines. This doesn't help the PHEV case, when batteries are depleted.
PHEV has its place, but at present, efficiency for long distance use is questionable.