Mitsubishi iMievs, in Raspberry Red Pearl. Then sell them. You'll have about 13 million left and so much RRP paint that your cars will all be a beautiful metallic dark pink.
visit the UCD every 2nd or 3rd race, and buy every cool car for 500K - 1.5M. rebuild their engines and chassis, take em for a spin with hard racing tires and no aids. rinse and repeat. This is how I enjoy my A-40 game from now. hurry up with DLC Please! PD, at least just an announcement of some sort, would be so nice. even if 2 months away, just announce anything! you'll still have that money left over for that "OMG THAT 5MILLION CAR IS THERE!" car. or you can buy that 1 really expensive 15 million car from the dealership, and weep at the next 5 really cool cars that go by in the UCD