Zax63

If you get an old body S65, renntech makes a flash programmer so you can go back to stock for dealership visits. Last time I checked (admittedly, months ago) one was not available for the 07 and newer body style. Perhaps that has changed by now. You could still CPO an late purchase 06, you could buy it in the high 40's with low mileage, CPO it and flash it up when you want more performance. I had the E63, and the S65 is much faster at the track. Funny thing, though... the E63 does feel faster. Once again, it is not faster, but it feels faster. I have discussed this with many of my passengers who have been in both cars. We have decided it is a few things... The S is much quieter, so the sensation of acceleration is not so Aural. The S is heavier, so all of the movements of the car are muted. And the ABC further isolates the car from the road, reducing the feeling of speed and the perception of cornering loads. You also get used to the power pretty quickly. But all you have to do is a get a passenger in the car who has never felt 840 ft/lbs of torque (renntech's don't provide max gains with just a flash), and their facial expression/verbal outcries are priceless.

rondocap

I think the OP wants excitement - I am the same way. Coming from an E63, he will not find that in a 65 - In my opinion, they are very smooth, and low-drama. I drove an SL65 recently, and was more impressed with the SL55. Why? The SL65 has very smooth acceleration, and does not create too much fuss. The 55 pulled more like a Corvette Z06 or something like that - even if it may be a bit slower on paper than the 65.

I think I also know why the 65 felt a bit tame, it's because I drove it back to back with a Porsche 911 Turbo. It was the 2007, which more or less will be close to speed with the newer Panamera Turbo. (The newer Turbo 911 is even faster, quarter mile in the low 11 second range, while the Panamera Turbo and older 2007 Turbo is in the higher 11's.)

So drive the Porsche...The looks of it are questioned, but I think it's unique and has a lot of street presence. The Performance of the turbo is unmatched in a 4 door car, and the interior is very nice. The PDK transmission is also amazing. I can't really think of a comparable car, as much as I love AMG's, they are still a bit too heavy and leaning more toward the comfort aspect of the performance range in the 4 door cars.

Mantooth

The CTS-V is faster than the E55, stock for stock. I just saw one with intake only put down 490whp and 502wtq, with just an intake. Add a s/c pulley and tune and he made 545whp and 591wtq.

pun1sh3rz

And the mods for the CTS-V are more realistically priced in comparison to the AMG platform.

It is high on my list for the next vehicle, good luck with whatever choice you make.