In article <3B93A9B8.E65CF3CD@brit.ca>, Trevor Boicey <tboicey@brit.ca>
writes
>Michael Hargreave Mawson wrote:
>> Most "headline" mileage figures are simply the highest figures that have
>> been achieved.
>
> Perhaps in the 60s, but ABSOLUTELY not today.
Really? It has been a while since I paid any attention to the figures
manufacturers claim for new cars, but I was under the impression that
most in UK still refer to the official "steady 56mph" figures. Maybe
things are better regulated on your side of the pond?
>> But how do you define them?
>
> There is a very specific formula for determining this
>figure. Combines urban and highway ratings in some preset
>ratio.
A ratio which presumably doesn't precisely match real-world usage except
in a handful of cases.
> I believe in the US it is called the EPA
>mileage estimate. This is the only one that can be
>put on advertising material, and it always has the
>asterisk next to it that refers to a note at the bottom
>that says "EPA mileage estimate".
>
> If you think about it, it has to be this way so that
>consumers can fairly compare cars from different manufacturers
>to see which ones are more economical.
Actually, I think quoting the three figures is more useful. If you are
buying a car for nothing but town-centre driving, having only the one
figure (based on a complex formula) is far less useful than knowing what
the "urban cycle" figure is. British Leyland actually took advantage
of this in the 1980s when it came out with the Metro "City" - a car with
an engine designed to be economical around town, but which drank fuel
like you wouldn't believe at high speeds.
>> "Fuel economy of up to 50
>> mpg" would still be a proud boast of any modern car manufacturer.
>
> Maybe for an SUV, but not for such a tiny car.
What does the Mazda MX-5 get, then? Seems a reasonable car to compare
with ours. And how about the Audi TT while we're at it?
>
> There are many economical cars today that achieve this
>figure for real, using standard "combined" mileage
>figures (ie: the same ones that saw the spitfire getting
>around 25mpg).
Hang on, that 25mpg figure was "urban cycle" - not a combination of
urban cycle and motorway cruising. Don't run our cars down more than
they deserve!
> And, sadly, generating more horsepower
>along the way. :<
>
> Case in point, the Insight hybrid makes 73hp and can
>also deliver 61/68mpUSg.
I don't know this vehicle, but the horsepower figure is very similar to
the 1500's 71hp. (That's English horses, by the way. I know French
horses are more feeble, and it is possible that American horses are
different as well...)
> First number is city, second number
>is highway,
I grant you that that fuel consumption is significantly better than that
of the poor Spit.
> but even the official highway measurement isn't
>the same as steady state 50mph consumption, it's more
>simulated back roads driving with some stopping, some
>starting, some passing, etc.
Really? Then I'm very impressed.
>
> I'm guessing what the Spit would be under those
>figures, but likely something like 25/32. A far cry
>from 50.
>
I think your guess is probably pretty close to the mark (in US gallons),
although you might get as high as 35 on the back roads.
ATB
--
Mike
Michael Hargreave Mawson, author of "Eyewitness in the Crimea"
http://www.greenhillbooks.com/booksheets/eyewitness_in_the_crimea.html
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