Warning: This is based on UK lawand anyone considering it should take advice.
If it is the wrong colour / spec you don't reject it. You don't accept it in the first place.
Rejection comes in if you take the car and go back later with issues. It would be difficult to reject a car based on wrong colour if you had not raised it at the time of delivery.
You have to give the dealer reasonable chance to fix the faults and if he cannot you can reject the car, it also needs to happen within a reasonable time of taking delivery (reasonable means the courts make the final decision)
Other wise all covered by Sale of Goods (& Services) Act - Google it.
If it is the wrong colour / spec you don't reject it. You don't accept it in the first place.
Rejection comes in if you take the car and go back later with issues. It would be difficult to reject a car based on wrong colour if you had not raised it at the time of delivery.
You have to give the dealer reasonable chance to fix the faults and if he cannot you can reject the car, it also needs to happen within a reasonable time of taking delivery (reasonable means the courts make the final decision)
Other wise all covered by Sale of Goods (& Services) Act - Google it.