Alistair, not sure about the S5 having same platform as the S4, the S5 had totally revised suspension, no longer inboard and had additional strengthening of the chassis, mine steered much more positively than my S3 which I put down to this.
When i was first looking I tried a few cars and this is the logic I came up with.
Open to correction, I just loved them all so may have missed a few things.
Series 1 ran for some time
286hp 4.4,
5 speed box,
centrelock wheels,
mostly low gangster hood but changed over time.
low boot but smaller
Narrow body within same width, small gap between steering wheel and door made for worry when adding a dab of oppo' for me.
VW lamps
Lighter and definately leads you to ragging it like a rental.
Insert GTN as a Series 1 AMG model with 4.6L and some changes around the suspension. Most holigan option, 10 made.
Series 2 was actually quite a make over to allow them to sell it in the USA.
Not many made and difficult to find
Next gen 4.4L with single variocam and 330 bhp
6 Speed box with nicer change
Uprated brakes with less fade
std wheels
Pram hood but better sealing potential (they all do that) , not so gangster 8(
Same road width but wider internals as doors moved out and running boards made more narrow.
More room around the wheel for those entertaining moments officer.
Petrol tank moved for US rear impact rules, rear boot line raised to give different rear look but bigger boot and shelf behind seats
VW Lamps, option of SIDEPIPES! from GTN
Series 3.
Mostly Series 2 but laser eyesight correction from the Mini headlamps.
Different wheels from factory
Sames engine,box,brakes,etc
Insert AeroMax, pretty.
Series 4
Lots of upgrades from the AeroMax development.
Single peice superform front wings/boards for easier access to service
4.8L double variocam V8 360+bhp
Auto option
Different cooling (gaps in front wings)
Updated interior
Double sidepipes, ha ha ha ha ha ha - drive by car alam attacks, neighbours muttering, big thumbs up from bikers.
Supersport (Targa) and Coupe (still leaks)
Series 5 All mostly S4 running platform with new body.
