quattro system?

[Steve Evans <sevans@radstone.co.uk>]

Reid,
>My engineer friend (who likes to start arguments)  insists that all 4wheel
>and All-wheel drive systems must suffer poor gas mileage.   I insisted that
>audi is competitive with most cars in gas mileage.  With the numbers to shut
>him up, he quickly changed his arguement to: These cars are severely under
>powered then.   Now being a finance Major, I don't know much about how the
>quattro works (I do, however know about how to finance them ;) ).   Could
>someone lend me some insight as to how the quattro system works?   Thanks in
>advance.

Under equivalent driving conditions a quattro will return better fuel
economy than as equivalent 2wd model. This is because a driven wheel under
moderate load has a lower rolling resistance than either a rolling, non-driven
wheel, or a more highly loaded one. Thus a 2wd drive car has both 2 rolling,
and hence high rolling resistance wheels (those at the rear) and 2 heavily
loaded wheels (those at the front) whereas a quattro has four moderately loaded
wheels, giving less overall rolling resistance. This effect is most
noticeable above
40mph.

On the down side (there is always one of those :( ), quattros, in particular the
urQ, have more power (otherwise expressed as a greater capacity to burn fuel),
than their lesser 2wd cousins, and given the natural human desire to exploit
what
we've got to the full, down comes the fuel economy again! If you have the self
control to drive a quattro exactly as you would a 2wd equivalent, then you will
see both better fuel economy and tyre wear.

Steve

'88 urQ
__
Steve Evans                             Radstone Technology Plc.
Principal Design Engineer               Water Lane,
                                        Towcester,
Tel: +44 (0) 1327 359444                Northants,
Fax: +44 (0) 1327 358113                NN12 6JN
Email: sevans@radstone.co.uk            ENGLAND