D3 vs d4
 

Having owned many d3s and 2 d4s,the latest being a 2012 d4 3.0tdi with decent spec,it is fairly obvious the d4 is not on par with the d3 on most levels,while the d4 may drive nicely,the quality and engineering is not there...
things like comfort sitting position and foot rest are wrong in the d4,with basic things like screen top tint absent,poor front storage and a boot almost half the size of the d3...mechanically the d4 fairs much worse too after over 200k combined d3 miles

Yeah I’d agree, and that sunstrip omission is so annoying cos the screens so big…. Miss my d3 all the time

Missing top tint LOL. I'd not even noticed this omission till reading about it here.
If it's such an issue, why not pop into a window tinter and get one applied to your screen.

My overwhelming impression when I first went from a D3 to a D4 is that the D4 feels, drives and goes around corners significantly better. The first drive put me right back into my D2 (yes I've had one of those too.)
The D3 is undoubtedly a fine car, but it took some effort to throw it about. Perhaps the non-V10s are dynamically better but I don't know having never driven one. They were well-built and still look good IMO.
The D4 doesn't visually do it for me the same as the D3, but I am continually surprised at the number of times strangers tell me how much they like the look of it.

The odd thing about the D4 is that the info/media system was already dated when they launched the car. It all works well but it's just a tweeked version of what is in the D3 and lacks much that is common cars of its age. And it's so slooow.

The engine (4L V8) is a masterpiece, coupled with an 8-speed gearbox that is also perfect. The former delivers power like no D3 could ever manage and the second makes seamless gear changes, and way faster than anything the D3 could manage.
Overtaking is effortless, cruising is very quiet and the suspension delivers smoothness or tautness as demanded by your right foot.
A bonus is this car's MPG. Three years in and it still amazes me.
Then there's the matrix headlights. These alone would swing me towards the D4.

Small boot? Nah, not an issue for me it's still huge.
Lack of storage in the front? I've never had a car with enough.
Footrest? Hadn't noticed.
Seats?. I love that the bolsters inflate once you're moving. I do find the big bolsters, say in the Golf GTi, difficult to navigate when exiting. Not a problem in the D4.
And comfort-wise, I can't detect any difference between the D2, D3 or D4. They are all great at cosseting over long distances.

Just need to try a D5 now. Fugly they are, but if they have progressed like the earlier models, they should not be to shoddy to live with :D

+1 Nick.
I really enjoy mine over four years in.