Most fuel efficient speed to drive?

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On 22 Sep 2005 04:45:03 -0700, mvl_groups snipped-for-privacy@yahoo.com wrote:


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
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Elliot Richmond wrote:

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!

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mvl_groups snipped-for-privacy@yahoo.com wrote:

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.
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mvl_groups snipped-for-privacy@yahoo.com wrote:

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
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On 22 Sep 2005 04:45:03 -0700, mvl_groups snipped-for-privacy@yahoo.com wrote:

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.
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