Most fuel efficient speed to drive?

Back when cars had carburetors, hard acceleration would reduce fuel
efficiency, because the accelerator pump in the carburetor would
squirt extra fuel into the carburetor each time the accelerator was
depressed. You could see the wasted fuel blow out of the exhaust pipe
as blaclk smoke.

With modern fuel injected cars, that does not happen. Instead, the
computer constantly adjusts the fuel mixture to the optimum ratio,
depending on engine speed and throttle setting. So I really don't
think it matters a whole lot.

A couple of years ago I read an article that suggested, based on
computer models, that is was better to accelerate the fuel injected
car up to cruising speed relatively quickly (not flooring it!),
because that would mean less time spent with a richer fuel/air mixture
and thus less total fuel expended. But that was a computer simulation,
not real world driving.



Elliot Richmond
Freelance Science Writer and Editor

 

on a p.o.s. detroit hunkohunk, sure. today, that still happens, but to
a lesser degree because it's more precise /and/ catalysts take the sting
out of the visuals for you.

yes it does - enrichment prevents flame-out. that's why it was done
with carburetted cars. and why it's still done with injected cars.
check out the megasquirt diy injector kit and read the source code if
you don't believe it.

including enrichment on acceleration!

 

MVL,
There are two car mechanics that have a column in many different
newspapers. They wrote a column on this subject several months ago. They
stated that an engine will last much longer if you have slow starts from
stop signs and stop lights. I don't remember whether or not they discussed
gas mileage related to this subject. I don't advise you to have a slow
start related to getting on freeways or interstates. In most cases, it's
best to have fast starts--for safety reasons when getting on freeways and
interstates. I hate it when people--especially really old people--try to
get on freeways on interstates while going at a really low speed.

 

Per Consumer Reports, some years ago, a "brisk" but not hard
acceleration is most fuel efficient. Slow accelerations are not
efficient either.

I have a manual transmission so I try to accelerate in 4000 - 5000 range.

If you're flooring the starts, there is no way it is more efficient than
what the transmission is automatically doing.

Cheers,
Alan

 

Downhill is good.

If you drive an Accord (with automatic) so that the tach even gets
momentarily to peak torque around 4500, you're going to be moving very
brisquely.

Which seems to mean that Honda thinks rather leisurely acceleration is
preferable, engine staying below 3k

J.