"John S." <hjsjms@[EMAIL PROTECTED]
> wrote in message
news:47b98ee9-9f79-45ed-a401-929b0c925579@[EMAIL PROTECTED]
> > MPG computers are very acccurate in my experience if you measure
> > average mpg over a full tank. The spot number also appears to be
> > quite acccurate.
>
> The spot number also gives you a pretty good idea of how much gas
> certain bad driving habits cost you.
It sure does. And it's a great tool for learning tricks to maximize
mpg too.
====
When I borrowed a friend's Golf TDI, which has an MPG meter, it was
interesting to see what did and didn't affect the reading.
- at a constant speed, if I relaxed the accelerator even very slightly,
the
MPG figure shot up to amazingly good figures (eg 80-90); if I pressed the
accelerator even slightly beyond the amount needed to keep a constant
speed,
it went down to about 40; at a steady 60 mph I was getting about 55 mpg
(all
thse figures are per *UK* gallon: multiply by 4/5 to get US mpg)
- the consumption at a given speed seemed to be about the same
irrespective
of whether the engine was hot (running for a long time) or cold (newly
started).
- changing up or down made surprisingly little difference: 50 in 4th or
4th
gear gave similar results with 5th only being slightly more efficient than
4th; however changing down in to 3rd (with the engine going at about 4000
rpm) was much less efficient, so there seems to be a cut-off engine speed
below which consumption is fairly constant but above which consumption
increases sharply
(probably both of the last two points are features of a diesel which might
not be true for a petrol engine)
- hard acceleration gave frighteningly low figures: a fairly brisk but not
wheel-spinning 0-60 through the gears, taking about 15 seconds, averaged
about 15 mpg :-(
- constant 30 was much much more efficient than slowing down to rest for a
junction and then accelerating away again; however as I came right off the
power when I was slowing down, I did get something like 300 mpg ;-)
- accelerating out of a roundabout in 3rd with a wider throttle setting
was
more efficient than in 2nd with the engine going faster, for similar
acceleration rates - again, probably a diesel thing
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