If it's a brand new car so there shouldn't be much to check. The dealer will talk you through the paperwork and explain various features of the car. Other than that, look over the paintwork to make sure it hasn't picked up any scratches or chips, as well as the lights and windscreen. Inside, check that it's all clean and as you'd expect for a brand new car. Make sure it's the specification you've ordered (including any optional extras), and take a look in the boot – make sure things like the tyre repair kit and locking wheel nut key (if fitted) is there.