Hi, I agree that if you're after detail then a contrasting underbody will look like you'ver really made an effort. I've always tended to think that if you cover the underbody with bed liner & then paint it, it looks like you wanted a different colour but couldn't be too bothered about putting in enough effort to do it properly. Yes, a smooth painted underbody is higher maintenence, but the overall effect far outweighs the effort needed to look after it.Best method would be to cover the baremetal in something like PPG Washprime,( assume you have this in the US) which is an acid based etchprimer,over-primed with a 2K primer, flat the primer where you want top surface type finish ie front clip, rear chassis legs etc & then coat with a good few coats of 2K colour. Under the wheel wells spray 2 coats of Stoneguard/Stonechip or whatever you call it in the US & once fully dry flat down to a smooth finish with 320 Wet & Dry & then colour that with 2K. I'm going to paint my '69 black but I'm going to paint the underside with dark metallic grey/charcoal colour & clearcoat it. It'll run all the suspension, axles & any othe parts I want to show as details in gloss black & assemble it all with polished stainless nuts 'n bolts. It'll be dark enough to be a contrast & will show that an effort has been made, plus it wont be too light in colour to show from the side profile, plus a darker colour is easier maintenance & will touch up ok. A dark grey underbody would suit a red car in my opinion, Hope that helps........Nigel