Drove these cars recently while helping a friend car shop.

The A5 had the Sport Package, among other things. The 428i was RWD and had the M Sport package, and that's pretty much it. Both were manual.

The best part about the A5 is its interior. Other than that, it's exactly what you'd expect from Team Jetta trying to build a 3-Series Coupe. Dynamically, everything it does comes up just short of being interesting. The 2.0T makes solid torque down low, so you think it might be a good engine. Then you notice it's nothing special on the top end, and of course the turbo-induced throttle lag is always there. Same story with the handling. It feels really surefooted all the time, but there's zero excitement. And there's pretty much no feel anywhere. The steering is lifeless, the shifter feels like it's in a different zip code from the transmission, etc.

The 428i might not have as nice an interior, depending on your taste. Its steering is comparably numb, and somehow it provides even less of a sensation of speed. But other than that, it absolutely kicks the **** out of the A5. Better throttle response, better engine notes, better acceleration. Better shifter. Better chassis by an order of magnitude. You can drive it like a normal person, and it feels like a really solid executive coupe -- or you can hustle it, and it feels sharp, responsive, and playful.

Overall, I didn't like either of them. Too numb and un-involving (mostly because of the steering), too gargly-sounding, and no razor-sharp NA throttle response. But if you value driving, holy hell does the A5 look silly next to the 4-Series.

 

My buddy has a 435i M Sport with the N55 single dual scroll turbo (same as my 2011 335i), coilovers and some other goodies, it's a blast in the canyons. It has now been replaced by the 440i and I bet that is even better with the new engine.

Audi's are okay but you really need the S or RS models to have a ton of fun. The BMW four cylinder turbos are okay but they feel anemic compared to the inline 6 turbo engines. My buddy has a F30 328i with some mods and a tune and I still pull bus lengths on him in my 335i.

 

I've driven a loaded 435i 8AT. Less fun with one less pedal, but you're right -- in terms of straight-line speed, what a difference vs. the 4-banger.

The steering really kills the experience for me, though. I've driven three pre-LCI F3x chassis cars and they all had unbelievably numb steering. Not quite so bad as the A5's, but that's an insanely low bar for a "sporty" executive coupe.

 

I agree - the inline 6 turbo engine or nothing.

 

If I had to have an F3x chassis car... I'm not sure which engine I'd pick, but I suspect it'd be the 4, honestly. Less weight, better weight distro.

Then again, if I had to have an F3x, I'd be bored no matter what was under the hood, so... :-P

 

^^ this has been my experience with late model German cars. Nice but boring. No steering feel at. all. I've no experience with modded Germans, but how much can really be done to improve 'communication' - driver involvement??
BMW has fallen a long way from the E36, E46 M3s. I came close to purchasing an E46 but every one I could find, even low-mile babied cars, were literally shedding parts.

 

I dunno, my 335i handles as well as my 8 with wheels/tires, the Dinan camber plates, and Bilstein coilovers, and while the steering feel is not as good as the 8, the power and refinement makes up for it. My 8 is just raw, and I like that, but it's not better unless you are talking autocross or something.

But they are just different animals. But drive an M1, M2, or M240i, etc and I think your opinion would differ. I do agree about the E46 M3 and I will own one.

 

The TL;DR of this is that the numbness is designed into the car from the ground up. You can tinker around the edges but you won't fundamentally change the car.

Anything you'd do to make the car more capable and responsive would help a little. Lighter, tighter, lower, louder, stiffer. It'll never be as good as if it were more involving and properly sorted in stock form, if only because there will be more negative side-effects. Like, by the time you stiffen things up enough to get some road feel, it'll ride like *** and STILL not talk much through the steering. Etc. But it's a step at least.

For post-2012 BMWs in particular, the cars are actually quite good in most respects, but two things ruin them: throttle response and steering feel.

Throttle response will always be limited by the turbo(s). To be fair, BMW seems to be way ahead of most makes in this respect. But even in RPM/load ranges where there's no perceptible lag, it still won't respond to throttle transitions as quickly and accurately as a good NA engine. And of course, outside of those RPM/load ranges, it's exactly what you'd expect from a turbo motor (albeit a very well optimized one).

AFAIK, the steering numbness is partly due to the rack and motor, partly due to the programming, and partly due to the suspension geometry. There's no fixing the rack and motor. Programming can be changed in theory, though that'd mostly affect effort, not feedback. Suspension changes would probably have the biggest effect on feedback, but good luck figuring out how to do that without screwing up more than you fix.
Theoretically the easiest thing to do would be to increase your scrub radius, but I don't know how much that'd do for you.

And if we're talking Audis and Mercs... just move on. They're so thoroughly designed NOT to be involving that it's not worth trying to fix that. (that's an oversimplification but you know what I mean)