Where to start with what makes the S5 and 335i different.
Well for a start interior design in the Audi is in a totally different class, it makes you (the driver) feel special before you have even turned the key or should I say pressed the key into the dash.
It's seats are brilliant as always, the MMI is better and the steering wheel has a nicer feel to it. The 335i is still a good place to be but unlike the M3 there is nothing else which is that special to say 'hey, OK the interior is average but the engine and chassis makes up for it', the engine on start-up is like any other BMW inline 6 which means it's pleasant unlike the S5 which has a note to compete with an AMG but only briefly, it's steering wheel is too thick and I know the M3's one is thicker but the leather is different and that makes a world of difference.
Now the actual experience of driving the two cars, firstly the 335i, it's a brilliant engine and pulls from very low down but to me the engine note is too civilised for it's own good but in it's defence it will pull all the way to the limit, it's steering is better mainly because it isn't as light but it wouldn't be anymore accurate than the S5. Turn in isn't as good which surprised me but then when you consider the extra width of track that the S5 has you see why it's better. Finally the brakes, sorry BMW but on this occasion the Audi brakes are much better and definitely stop quicker.
Now to the S5, as I have said 'what an engine note', it's a real head turner even when they haven't noticed the looks and when you do happen to open it up it just makes you feel much better and more special. The steering in the 335i is better but I think this is down to not being used to the lightness of touch but it is in touch with the surface and you can feel the transfer of grip from one axle to the other which I never felt the same in the old S4 so the chassis is making a difference and as I have already reported this is the first S model which does get pretty close to the feel the RS4 give in a corner with all of the confidence that goes with it. The brakes are impressive and on road work at least seem resistant to fade. Also the ride in the S5 though slightly firmer than the 335i (S/E model) it feels better for traveling quickly and this time round isn't at all bouncy which I dislike about the old S4.
As for performance, well as I didn't drive the cars back to back I can't comment on which is the quicker, I reckon the nod would have to go to the S5 but this may be down to the rest of the experience, the noise etc, but going by what most of the reviews are saying is that the S5 is about a 0.5~0.75s quicker to 100mph which would be equal to 2~3 car lengths. I will say that when in a higher gear I reckon the 335i pulls the harder or at least seems too.
Did I make the right choice.......................
YOUR BLOODY RIGHT I DID.