From: "Geo." 

Because the engine idles fast enough that if you take your foot off the
brake you move forward.

Geo.

"James Adams"  wrote in message
news:3E22C121.E00F9901{at}compuserve.com...
> > It helps you stop too, it keeps the front wheels from locking up while
the
> > rear wheels are still pushing.
> >
>
> 'Fraid you lost me there.  If you're braking why would the rear wheels
> still be pushing?

--- BBBS/NT v4.01 Flag-4