Again, there are better authorities than I but......
I did exactly this a few years ago, except my drive has a fair slope which made it a little more complex.
Firstly the gravel must be retained, make sure there is at least a 50mm lip around it, up to the final projected level. Its gonna get scattered anyway, but you want to minimise things.
Due to my slope, after spraying for weeds and putting down weedmat, I put in a 75 mm layer of road base. This compacts like concrete and gives the surface gravel something as a key to stop it sliding down the hill.
I chose white, quartz gravel. Luckily I had a mate working for a big quarrying company which kept the price down. The thing to ensure here is that its the right size. I think mine was 15mm screed. Any smaller and it gets stuck in the tread of the cars. Take advice from the quarry who should know this stuff.
Dont put down more than about 50mm. It will slowly compact and become fairly rigid. Any more than 50mm and you'll have trouble getting traction with the tyres.
Hope you don't have teenage boys with cars, they'll do wheelies just to hear the gravel fly.
Good luck