Contain your enthusiasm for a moment, and before you hit the road start thinking with the critical part of your brain.
Initially you must check that the car is exactly what you ordered. Is every extra and option that you specified actually on the car? If you ordered automatic climate control and the car only has ordinary air-conditioning, don't accept it because, whatever the salesman says, the two systems are completely different in the way they work and there is usually a price difference as well.
Before you leave the dealer, as well as checking you've got everything you paid for, look over the car very carefully for any dents, scratches or paint faults outside or for any trim damage inside. Carry out that check in daylight and don't let the salesman rush you. Check everything you can - and that includes ensuring the radio works.
People who know the car trade avoid sales peaks like August because they know that most pre- delivery inspections are rushed at this time.
Having checked all the things you can see, you must always prepare yourself for the possibility that the car has some damage or defect that only becomes apparent after you drive away.
Under the Sale of Goods Act 1979 and the Sale and Supply of Goods Act 1994 you have the right to reject a car you think is unsatisfactory or to have it repaired free of charge.
Legally, if the car goes wrong after you leave the dealership, you must act within a "reasonable period of time". That is usually defined as two to three weeks and the defect must be pretty major for you to be able to reject the car: a blown engine or failed gearbox are major enough.
If your new car is repaired by the dealer, never sign a release note saying that the work has been completed satisfactorily until you have checked that it has been.
An important point to bear in mind is that as a consumer your rights relate to the contract you have with the supplier of the goods, not the manufacturer.
Most car manufacturers and importers have excellent customer relations services to resolve disputes between customer and dealer, but in law your argument will always be with the dealer from whom you bought the car. The dealer is not owned by the manufacturer or importer; it is an independent business with a franchise.
New cars usually arrive in A1 condition, but be sure not to take that as read.