> > Interesting figures. Apparently ,according to the on-board computer, my
> > wife's 1.9 TDi Doblo is as good as the matchbox Aygo?
[quoted text clipped - 3 lines]
> filter ripped out and replaced with what looks like a K&N - and that milage
> is on petrol - I get similar on gas - 55mpg round town - nice!

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David G. Bell -- SF Fan, Filker, and Punslinger.
"I am Number Two," said Penfold. "You are Number Six."
> On Friday, in article <dhg0k3-5gl.ln1@linux.site>
>
[quoted text clipped - 9 lines]
> stop-start motoring than constant speed. And the differences between
> 55mph and 75mph are pretty big.
When comparing like-for-like designs that is true, but aerodynaics
have to be taken into account when comparing differing designs. As
a rather radical example the power used to overcome drag (as a
percentage of fuel used) is way higher on a motorbike than a
family saloon - motorbikes are (surprisingly) terribly inefficient
at speed.
> But engine types do matter, both sensible power-weight ratio and general
> efficiency.
Agreed - an engine that is suitabe for off-road use is never going
to be as efficient, particularly at high speed, as one designed for
high speed from the outset. LR got a Queens Award for Technological
Achievement for going some way to wards resolving this with the
300Tdi.
> A lot of this can be masked by driving style. I know that I routinely
> drove with better MPG figures from the 'puter than my father did.
Tyre pressures can make the biggest difference on a "family saloon",
perhaps not so noticable on a Defender!
> Personally, I don't desire to drive along motorways at 100mph, but a car
> that has the power and handling to safely sustain that speed is a lot
> better at 70mph than a Smart with the engine running flat out. That
> doesn't mean it has to be all that much bigger, but the design
> optimisations are different.
As you say, it depends on the design of the engine - small engines
can be very efficient at high speed if that's the design goal (not
that that's much good in a car designed for going round town like
the Smart). I've often wondered what happened to the Japanese
research into ceramic engines in the 80's - they had tiny, very,
very high speed engines producing prodigious power but they
seem to have faded away.
> For a while, 4x4s were the only car-like vehicles that had the features
> needed by a larger family. There are alternatives now.
Sort of - the Espace concept was bought off Chrysler Europe and
put into production about the same time as 4x4's started being
used as Chelsea Tractors, but failed to become fashionable until
relative recently. Plus as they tend to be driven by the very
people who complain about 4x4's, they are not going to be looked
at very carfully. (See the post on this group about the Anti's
in Tesco's car park a few weeks back).
Richard

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Tim Hobbs - 19 May 2006 17:45 GMT
>Tyre pressures can make the biggest difference on a "family saloon",
>perhaps not so noticable on a Defender!
It's a major cost factor for commercial vehicles too, especially given
how many tyres they have on the road.
I'd have thought that sidewall depth and tread width would be big
contributors, both higher on a Defender than an average Eurobox.

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Tim Hobbs
'58 Series 2 88" aka "Stig"
'03 Volvo V70
'06 Nissan Navara aka "The Truck"
Richard Brookman - 19 May 2006 17:54 GMT
|| As a rather radical example the power used to overcome drag (as a
|| percentage of fuel used) is way higher on a motorbike than a
|| family saloon - motorbikes are (surprisingly) terribly inefficient
|| at speed.
Indeed - hence the way that even a modest sports bike will out-drag a
Ferrari up to about 80mph, but the car will sail past once over the ton,
however powerful the bike.

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Rich
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