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From: arnold@ucsfcgl.UUCP (Ken Arnold%CGL)
Newsgroups: net.auto,net.legal
Subject: Re: 70 mph fuel economy
Message-ID: <627@ucsfcgl.UUCP>
Date: Sun, 1-Sep-85 17:51:14 EDT
Article-I.D.: ucsfcgl.627
Posted: Sun Sep  1 17:51:14 1985
Date-Received: Mon, 2-Sep-85 09:22:34 EDT
References: <1081@homxa.UUCP> <4891@allegra.UUCP> <155@iitcs.UUCP> <553@unisoft.UUCP> <492@lasspvax.UUCP> <188@cornell.UUCP>
Reply-To: arnold@ucsfcgl.UUCP (Ken Arnold)
Organization: UCSF Computer Graphics Lab
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Xref: linus net.auto:6958 net.legal:1898

In article <188@cornell.UUCP> prins@cornell.UUCP (Jan Prins) writes:
>In article <492@lasspvax.UUCP> chu@lasspvax.UUCP (Clare Chu) writes:
>>
>>    Correct me if I'm wrong but I heard that some of today's cars
>>    get better mileage at 70 mph.  (16-valve 4 cyl engine???)
>>
>>                                     Clare
>Attractive as this thought is for the anti-55 crusade, I think it's unlikely 
>to be correct.
>                                                3
>It's the tyranny of air drag:  P = 1/2 rho CdA V  . ...

I have come to the same conclusion as Jan, but not because of fancy
calculations, correct though they may be.  Quite simply, most cars sold
today in which mileage is a factor are sold on the basis of EPA Mileage
Estimates, which are conducted at 55mph.  Thus, the better the mileage
*at 55mph*, the better the stats, and thus the more the mileage works
in favor of a sale.  Any smart company would put a lot of effort into
creating an engine which is highly efficient at that speed.  The only
people who would design engines more efficient at higher speeds are
people who are selling to people who don't care about mileage, such as
Rolls owners, or who care more about speed, such as sports car
enthusiasts.

		Ken Arnold