You have a bunch of different options that are very far apart.

I have a 2006 S65 AMG (same engine as the CL65, and similar car as well) and it's an amazing car. Would be great for a daily drive (assuming fuel is no problem because this baby DRINKS).
You're talking about tuning it? Have you driven it before that you want to tune it already? My car sometimes spins the rears at 80mph under hard acceleration from all the torque...

Sensitive issues with this engine are the ignition coils and turbo valves. The coils are extremely expensive as well, I replaced both coils a few months ago, almost $3000 only for the coils, labor is expensive as well for that job.

Jumping from S65 to the 335i or the 996tt is just a different world. The S65 is just a mad powerhouse that never stops but it's not sharp to drive. It's buttery smooth, in everything and pops your eyes out accelerating and braking.
If you're considering the 996tt, well it's probably more reliable than Any Benz, it's much sharper and more fun to drive, can also be significantly lower on fuel. In all the Benz cars you're looking at traction control CANNOT be disabled completely (including mine). Even while "OFF" it still catches you if you slide too much. I hate it, but I guess the car needs it.

Decide if you want an SUV. Do you need to take a lot of crap in the back often? Do you do outdoor sports you need the room? If not I would just cross it out.

The S8 is interesting but make sure you drive it, I drove a new 2011 S4 this summer with a friend who works at the dealer, I pushed the car and Audi makes their cars understeer A LOT due to safety. It's also less comfortable and very harsh (suspension). I found it lacking, the BMW 335i /sport package is a far better car in my opinion.

If considering the M6, I would take a look at the M5 as well (I would go for the M5). The 6-series has useless room in the back, people CANNOT sit in the back and the car is HUGE and it doesn't feel huge inside.

If you will be more specific with what you use your car, what is more important to you, what you are willing to live without etc...

Hope this helped.

 

I have not driven a 65 series Mercedes, but I have had a bit of seat time in a few VERY high horsepower Supras. Imo, if the power's already there, why not take advantage of it?

Aside from recoding certain pieces of electronic equipment, I can do the maintenance myself. You say that you replaced "both" coils? Do you mean to tell me that the all mighty M275 engine does not use a COP setup??

I've driven both the S4 and S8. Imo, the S8 is a luxury car with a sporty engine. In has a large beautiful interior, rides very smoothly, and approaches being too quiet. The car is also very heavy and feels slow when compared to the M6.

Specifically, I don't need back seats.. At all. It just so happens that the SL65 is priced right at the upper limits of my budget and the other two 65 series cars have back seats. Same situation for the S8.. The R8 is out of my price range and the S8 is my #2 choice.

What I enjoy:

-Tuning potential (engine, suspension, exhaust, really anything mechanical)

-Forced induction (goes hand in hand with tuning potential, and love the sound of turbochargers)

-Build quality (I hate squeaks, rattles, groaning, crashing, etc)

-Looking over my shoulder as I walk away from the car

-Non dealer parts availability

-Forum support beyond new wheels, interior trim, body panels, stereos, etc.

-Coupes (I couldn't care less about the convertible aspect of the SL. If they made it in a true hard top I'd prefer it. Same goes for the 996TT... why do they all have sunroofs?

-Enough space that my knees aren't in my face while driving.

-Control of the gearbox. I've become skilled enough with the manual transmission in the E28 M5 that I quite enjoy driving it. I'm no pro (far from it actually), but I've got the whole heel toe thing down and it puts a smile on my face. I also feel that I could learn to love smg.

-The absence of unnecessary over-engineering.. ABC suspension being case in point. Have to say, the whole R129 electronic throttle body/bio degradable wiring harness debacle left a bad taste in my mouth with Mercedes. I've been extremely busy with school lately and haven't had the opportunity to tie up all of the loose ends with the car, but more info can be found here:

http://www.peachparts.com/shopforum/...ky-faults.html



Thanks,
Craig Rhyne

 

You've mentioned having a pet peeve for rattles and squeaks at least twice already. I will say that the 996TT is not free of the occasional noise here and there, especially over bumps. Someone just posted a thread with some spray products to help alleviate this, but take a close listen to any car you're test driving and get on some less than perfect roads. When I took my test drive all the roads were smooth as glass, so I didn't have the full picture.

 

You can find a slick top 996 as well, they're just much harder to find.