RR Classic: difference between 3.5 and 3.9?

And before you say it.....don't say 0.4!

What's the differences, as in, I know its obviously 400cc engine capacity but does it represent a different series or trim of model, and is it significant enough to worry about? Big difference in performance? Any known reliability issues with the 3.5 that were solved with the introduction of the 3.9?

Introduction of the 3.9 saw porous block/slipped liner syndrome as it is a 3.5 engine bored out larger. 3.9 also has fuel injection and is more reliable in that regard as opposed to the distributor fired 3.5. That said, the 3.5 is a sturdy reliable plodder which is easier to maintain from a DIY point of view and has fewer troublesome electronics. The later 3.9 Vogue SE in my opinion, apart from potential engine problems was a superb motor. I had to replace the engine in mine due to block problems-she ran superb after-and I wish I had not let her go.