[Hydroglen]

The issue of fumes varies from car to car. It depends largely on the roof
line and design of the trunk (boot) and the angle of the exhaust pipe.
But why would Hillman go to the expense of fitting an opening window, and
then tell you not to open it? Maybe it was for necking couples, who having
parked in a secluded lay-by, wanted to avoid steaming up the windows!
Dorien