I wouldn't like to say how well you'd do negotiating the main dealer price down, never tried with BM, are you trading another car, if so it's the price to change that's the important one.

It could be that the BMW approved car is in slightly better condition bodywise as they will get first choice if the car is a defleet/closed auction souced, course it could be their own trade in from a preious customer too, you'll have to ask.

Thats not to say the CG car won't be a perfectly decent car too, you'll have to go on condition, mileage, service history, specification etc same as any car.

'premium for approved car'....hmm that really depends on whats likely to go wrong in the first year....my own thoughts would be very little if anything, so with this particular car i would be very happy to save a couple of grand, but i'd want to check and test drive the cheaper car thoroughly, that may not be so easy.

Is there really a £3K difference for identical specced/mileage/month of 07 cars between the two, or are some lower spec/higher mileages/older/minor dents and scratches.

If the real difference between two identical cars is £1K then i'd be having the assurance of a rock solid BMW approved used warranty which IS worth the paper it's written on.

Also have a look at the warranty. I haven't got experience of Car Giant etc either, but IU'd imagine that whatever warranty you get will be fairly basic with lots of exclusions.

BMW dealers will have some form of BMW-sponsored warranty.

Alternatively, try a BMW used car specialist. My Z3 came from James Paul near Horsham (google James Paul BMW and you'll find them) and although seven years old was immaculate. They gave a 6-month warranty and I bought a further 2 years for a reasonable amount..