I'm thinking of getting a spoon oil cap and radiator cap. Anyone have them or know if they will fit before I go and order them?

 

I just bought the Spoon radiator cap for my 01 CLS. As long as you've got a Denso radiator in your 03, you'll need the Type D cap. That's the one I bought and it fits perfectly. Spoon only makes 2 types, D and F.