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From: dcn@ihuxl.UUCP (Dave Newkirk)
Newsgroups: net.auto
Subject: Re: Less Is More?
Message-ID: <1679@ihuxl.UUCP>
Date: Thu, 9-Jan-86 09:15:09 EST
Article-I.D.: ihuxl.1679
Posted: Thu Jan  9 09:15:09 1986
Date-Received: Fri, 10-Jan-86 05:23:13 EST
References: <25300019@gypsy.UUCP>
Organization: AT&T Bell Laboratories
Lines: 34

>   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.

>   3. If rapid starts and quick acceleration wastes fuel (another
>      U.S. Gov't. contention) then how can up-shifting as quickly
>      as possible save fuel?

I think the Gov't had automatic transmissions in mind here, since
early up-shifting does help fuel economy in stop & go traffic.
But early shifting doesn't mean spinning your tires at stop lights
to get to second gear faster.  Some moderation is required.  In
my Saab Turbo, I try to hold acceleration at or below the beginning
of the boost range while up-shifting just under 2000 rpm.  This
seems to give you an extra few percent in economy.  If you tried
this with an automatic, it would work just the opposite.  The
harder you accelerate, the longer the transmission holds you in
the lower gear.  When you decelerate, then it up-shifts!
-- 
				Dave Newkirk, ihnp4!ihuxl!dcn