On Tue, 10 Aug 2004 09:31:42 +0100, Dave Plowman (News) wrote:

For instance, the type of nozzle for Diesel could be shaped in such
a way that it would not fit on a petrol-driven vehicle, and vice
versa.

It already is...

Only for a car that must, normally because it has a CAT, have
unleaded. Though I guess there aren't many cars, in normal use, that
are old enough not to have a CAT.

--
Cheers
Dave. pam is missing e-mail