I'm looking to buy a C280. Can someone clarify if it's a straight 6 or V6? I know older models were straight 6 but kbb.com tells me the 99 model is a V6. I'm confused. I know the straight 6 had fairly common head gasket issues. If the 99 model happens to have a totally different motor (V6) did it have any common major issues such as head gaskets problems?