recommended tyre pressures differ from vehicle to vehicle and is dependent on the tyre, wheel size, load etc. ive always had 32 on the front and 30 on the rear and never had any problems with regards to fuel economy or tyre wear. not sure what you mean by the term 'light car' as this is not a recognized catergory - unless you are refering to a private or light goods vehicle?
EDIT :- Here are the recommended tyre pressures for my car, or any other mkII Leon FR TDI for that matter :-
Tyre Pressure results for the following Car:
Make: SEAT
Model: LEON
Spec: 5 DOOR HATCHBACK - 6 SPEED MANUAL - DIESEL
Trim: TDI FR
Engine: 1968
Introduced: 06 MAY
We have found 1 tyre size that matches this vehicle.
Tyre Pressures, for this vehicle, are as follows:
Front Tyres
2.2 BAR / 32 PSI
Rear Tyres
2.0 BAR/ 29PSI
so it would seem im 1 psi too high on the rear, i wont lose sleep over this