-------------- 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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