[Shotimes] Speedo Error... was: My MPG Test is Working!!

[Sean Simons]

Perhaps the GS has the "wrong gearing" for gas mileage on purpose. Rather,
to improve it's 0-60 performance to look good on paper. Changing the wheel
size is an easy way to change that balance, as far as I can guess. Tyler
Garlock was able to pick up a lot of time at the drag strip when he put drag
radials on his SHO. Of course, there was extra grip, but they were MUCH
smaller than his regular wheels. I'm sure the size made a difference.

Sean Simons
black '89 "Super Geek SHO"

On 8/15/06, krazgeo@comcast.net <krazgeo@comcast.net> wrote:
>
> -------------- Original message ----------------------
> From: Alan Fanning <Awfanning@earthlink.net>
>
> > If a 5% reduction in final drive ratio nets an improvement of several
> mpg's,
> > I question what the manufacturer's were thinking in not taking advantage
> of
> > that.
> >
>
> This fact is what brought the whole thing to my attention.  We borrowed an
> '05 RX330 from the Sac Lexus dealer last summer, while Eva's (now sold)
> RX300 got some diagnostics, and drove it over Donner Summit to Reno and
> back.  While working the tranny manually while using CC, I was able to get
> about 25 mpg average while going 65 mph, when her 300 would only get about
> 18 on that trip.  Its engine turned 2900 RPM at 65, while the RX330 turned
> 2200.  With her driving around town, she didn't even get 14.  The 300 had
> GPS, while the 330 didn't, but had a trip computer.  My GS doesn't have
> either one.
>
> I discovered on the trip home (I-5, at 70 mph) from Oregon that the GS
> still doesn't do as well as I'd like it to above 65 mph.  At 70-72, it drops
> down to somewhere around 25, while it will get 30+ at between 60 and 65.  We
> averaged about 27.5 on the I-5 trip home, when I would have expected it to
> be at least near 30, after the previous day when it beat 30.  The majority
> of that earlier trip was at 65 and then 55 in Oregon.  It's going to be too
> hard to lower the engine speed by another 300 rpm or so, so I'll just live
> with it.
>
> I discovered a similar rapid drop in mpg in my '78 Fiesta, which now is
> owned by Jim Koper in Ohio.  After it got its '98 European engine through
> rebuilding, it got REALLY good freeway mileage (32-35) below 70 mph, where
> it crossed over the 3000 rpm range.  Above that speed the mileage dropped
> down to about 25.  So that is two vehicles I have seen where an engine speed
> change of just a few hundred RPM makes a large difference in mpg.
>
> I'm still keeping the GS till the wheels fall off.
>
> George
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