On Monday, 12 March 2018 00:20:04 UTC, Fredxx wrote:
On 10/03/2018 21:29, tabbypurr wrote:
On Saturday, 10 March 2018 18:41:58 UTC, Dave Plowman (News) wrote:
In article ,
David wrote:

The motor manufacturers will have to produce a new range of economical
petrol engines targeted at the big load luggers which do so much of the
utility work before diesels can be phased out.

Petrol engines are at their worst efficiency wise when doing stop start
journeys.

all engines are

At cruise, nothing like the same difference between petrol and
diesel. And diesel can become less efficient when thrashed.

all engines do

That's not the case for petrol. There are no induction losses for one
and if you don't allow the revs to go to far above max torque.

If you've ever seen efficiency plots for car engines you'll know that worsening efficiency when thrashed is inevitable. Much worse. If you understand engines reasonably well you'll also know why.


Hybrid technology gets round the problem of poor efficiency in stop start
conditions.

does it? The Toyota Priapus gets worse combined cycle mpg than a straight engine.

Even for city driving?

The only thing that counts in the real world is total miles per total fuel consumed. Splitting it up into bits is of little utility. Hybrid engines sounded like a cute trick, but have not delivered.


NT