Crikey what a question! But given a euro millions there are a couple of candidates.
956 017, New man joest car. May not be the ultimate driving experiance but its historic value is huge.
If i had to choose an f1 then it would be a ferrari 312, I don't think they went into numbers back then, but if ickx drove it I would be happy.
For fun it would have to be 70's 2 litre chevron, I doubt any has any greater value than another, so any B36 would do.