At 08:30 PM 1/21/2002 +0000, you wrote:
>Hi hugh, I get almost exactly the figures posted in your PM article with
>my 1958. Maybe a little better (13.4) at a sustained 70mph. Perhaps my
>electronic ignotion helped a bit!
More likely its your radial tires vs the original cross ply. The rolling
resistance is much lower. Also, keep in mind that the gas mileage people
report is based on the odometer readings. These are not always as accurate
as we would hope. Part of the reason is the tire sizes and rolling
diameters are now a bit different. In the 66-69+ model years, the
235/75/15 used is very close to the original 9.15-15, although not all
agree as to what the exact difference is. On my 68 sedan, the odometer
under-reads by about 3% which is a very small difference (indicating my
235/75 are just only slightly larger than the original 9.15) while my 68
Lebaron under-reads by over 10% (this is more likely instrument error which
is very strange as the speedometer is more accurate than the sedan in the
usual speed range!). The point is, the "absolute" reported values can
deviate some, and odometer errors could be the cause as much as engine
tune. As said by somebody else, its more important for your mileage to be
consistent with what you "used to get" in the past, rather than how it
compares with other reported values. Of course, if you estimate 8mpg on
the highway at 70, there is something wrong! D^2
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