Quote:
Originally Posted by HighlandPete
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.
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I did just touch on this on my post above - I haven’t found that to be the case. I’ve driven an F31 328i and F31 335i with engines both one gen old now but the difference was quite big on flat roads at a constant speed. About 20% difference in fact.
However from Napier to Taupo which has a large number of hills and some quite twisty bits there was a much smaller difference, about 10% and the 328i definitely needed to be pushed quite a bit harder.
The big thing here probably is that the 335i could drive up the hills and out of the corners with ease and not making a huge amount of boost, in turn keeping the AFR much closer to 14.7 for longer.
100% agree about the 330e and 530e being flawed. Mainly because of the 46l tank limiting range At least the X5 PHEV has a bigger fuel tank and larger capacity batteries. If you could physically fit that drivetrain into a 540e or 545e with a 60-70l tank it’s be a great car