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From: mat@mtx5a.UUCP (m.terribile)
Newsgroups: net.auto
Subject: Re: Re: Less Is More?
Message-ID: <1183@mtx5a.UUCP>
Date: Tue, 14-Jan-86 00:04:00 EST
Article-I.D.: mtx5a.1183
Posted: Tue Jan 14 00:04:00 1986
Date-Received: Sun, 19-Jan-86 04:42:47 EST
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> >   1. If the engine is running at 2500 RPM, what difference does it
> >      make what gear I'm in or how fast the car is moving?
> 
> If you had a boost gauge you could tell that at 70 mph, the engine is
> working harder that it was at 30, even if the engine RPM's were equal.
> After you pass ~40 mph, wind resistance becomes important, and at higher
> speeds it the major resistance to overcome.  It's like going downhill
> in gear (high vacuum) and then going up a steep hill (low vacuum) at
> the same revs.  You're going to burn more fuel to get up the hill.
>  
> >   2. If Toyota says that going faster saves fuel, and the U.S. Gov't.
> >      says that going slower saves fuel, who is right?
> 
> No matter what kind of car it is, your fuel consumption increases with
> speed.  Depending on the aerodynamic drag of the car, the rate of
> increase differs.  Since an Audi 5000 has less drag than a Chevy
> van, it could go much faster with same amount of fuel consumption.

This assumes that in neither case is the engine being operated in an
inefficient part of its speed/torque range.  The problem is just NOT
all that simple.  After all, with a manual transmission, you CAN get
better fuel economy in many cars by accelerating with about 2/3 of the
throttle, and upshifting as soon as possible.

BUT with all manufacturers building cars for the CAFE requirements and
testing at 50-55 MPH, most cars will have their fuel economy ``knee''
pushed up into the 50-55 MPH range, and pushing that knee on the curve
will probably make the drop-off steeper afterwards.

Because the CAFE requirements average all cars sold by a manufacturer,
less-widely sold lines can be built to be way off average.  This includes
'vettes, of course.
-- 

	from Mole End			Mark Terribile
		(scrape .. dig )	mtx5b!mat
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