Update: I went for a test drive today - I drove this E60 M5
https://www.hannaimports.com/used/BMW/2008-BMW-M5-raleigh-nc-2c690a620a0d04fe0f193c0f1c2b8aaa.htm
Couple of important caveats - Much of my feelings below are due to owning and daily driving a tuned F10 M5. So keep that in mind, especially as I talk about the engine. Second, I still love the e60 M5, so please don't think I'm bashing it in any way, just giving my opinion. Lastly, it's important to understand the progression of cars that lead me to this point, so you know what I'm comparing to. I won't bore you w/ all the non-BMW's but essentially I went from 2003 330i ZHP (6speed), then E90 M3 Slick-top (6speed) and an e46 M3 (6speed) at the same time, finally to an F10 M5 (DCT).
Initial thoughts - I left feeling very "underwhelmed" and quite frankly, disappointed.
First of all - the pics make the car out to be quite a bit cleaner that it really is. The car has been on the lot for 176 days and it shows. It's been scuffed; scratched and the interior is not in great shape. Sitting out in the elements has clearly taken it's toll. A-pillar cloth is beginning to sag, shifter trim cover is bubbling/peeling. The top rear bumper/trunk area is all scratched up; Seats are worn, carpets are dirty and it has a bit of an odd smell...not sure what, dog maybe? I guess I wasn't expecting the e60 platform to age so poorly; not sure if it's just this one or all of them are starting to get long in the tooth. All of that being said, based on what you guys wrote above; this was kind of my expectation, but I guess seeing it in the flesh put a new lens on it. I guess I'm more disappointed with this particular example, which clearly didn't age well.
On to the engine. Not sure if this car was running right but even in "power" mode; i.e. all 507 ponies; it just didn't sell me. It didn't "stir my soul". The induction sound was great of course but...I don't know, I expected more. Granted, this was a bone stock car. Maybe I'm spoiled by a tuned F10 M5 and the stupid torque and non-linear delivery. It feels like for this e60 M5 to be "fun" for me, it needs a tune, intake, and a muffler delete at a minimum. Of course I would do those things anyway, but again, this car left me a bit uninspired. I couldn't even hear the exhaust note, which was rather disappointing.
The SMG Trans...oh boy....I am not a fan. You guys are right, I'm sure there's a certain way to drive it but I just haven't found it yet. I thought I loved a firm shifting car and again, maybe I'm spoiled by the DCT but even at full strength, the SMG is a bit slow and too violent or "jolty", especially at full tilt. Is there a way to improve that? Maybe the Euro software of FAMS tune? Interestingly, the lurching about between shifts in low speed traffic didn't really bother me. I think I could live with that. Maybe the s85 goes better w/ the 6 speed manual; maybe not.
Suspension...so this is an area where I was thoroughly impressed. Yes there was some body roll but the car felt sharp, if not a tad bit harsh, planted and overall, did NOT show it's nearly 100k miles or 4k+ curb weight. Wonder if it had the suspension redone (control arms) or refreshed somewhat recently? It also felt a heck of a lot more nimble, tossable and overall more "fun" than my F10. Miles more fun I'd say. Not e90 M3 levels (or e46 m3), but not as far off as I would've thought.
Overall, I've come away feeling like the e60 did not strike me as a car that could take the place of the F10 as my daily, and it wasn't "fun" enough to warrant 3rd car/weekend car status either (maybe a manual would be different). I think if i had to do it over again, the right move would be to have bought an e60 M5 after the E90/E46 M3's or, an F80 M3. I think the driving experience/engagement gap from the manual E90/E46 M3's to the DCT F10 M5 was far too much, which has now left me "missing" that engagement. Not sure what the outcome of this exercise was, other than education for me, but I will still keep my eyes open for a nice e60 M5...or a nice e9x M3, or e46 M3 lol. If you've read this far, thank you!