I actually own a 2008 ISF and a 2011 Mercedes C63 AMG with about 500+ hp to the crank. Yes, the C63's acceleration is awesome but it just doesn't feel like I'm in a high performance car. It's fast, but it's not as responsive and quick in going thru its gears compared to the ISF. It makes me feel very old and the center console reminds me of a VCR. I can say that Mercedes used to be very unreliable but now, they are pretty reliable but no where near Lexus.

My 2008 ISF feels better and handles better than the C63 and both of them have no handling upgrades. I have never driven the 2011+ ISF and I would really want to see the performance gain from just a few tweaks. Also, you are correct with the fact that ISF's are rare. Let's say there are 10 cars consisting of ISF, C63, & M3. I would say 6 of them are M3's, 3 C63 AMG and only 1 of them being an ISF. Furthermore, I have the Matador Mica Red, and I've only seen three of these since ISF first came out in 2008 which makes it more rare. I get a lot more stares and compliments with the ISF than the C63. I would say... For every 1 compliment for the C63, I get like 10 for the ISF. The ISF has nothing but straight pipes with vibrant resonators and the C63 has Eisenmanns along with a CF front lip and CF diffuser for aesthetics.

 

I can see why JORDANAF would buy another C63, especially if it is a '12 and up. I just recently traded in my '12 SPW IS F for a '13 C63 sedan based on extensive research and a very long test drive. sjpbug, the '11 and up IS F handles way better and in the 2011 VIR Lightning Lap it actually matched the M3 coupe with an upgraded suspension option to the tenth of a second. They both beat the '11 C63 time wise. Now in '12 the suspension was revised in the C63 and the transmission (multi-wet clutch) is also redone to enhance shift times. The C63 shifts every bit as fast as my '12 IS F in my opinion. The interior is also really nice and matches the IS F but with a bit more attention to detail. The gauges are more old school looking but I personally like that. I only have 293 miles on the C63 but I can say that whereas I had multiple cars and even trucks wanting to race the IS F, no one to date has messed with the C63. Curiously, I only had a few questions as to what the IS F is and never any thumbs up or such but I have noticed more that a few stares at the C63 (with the P31 package) probably due to the exhaust note. Anyway, both great cars but I do like the torque in the C63. Reliability wise, well that remains to be seen but I took out and extended warranty on the ISF and now on the C63 just in case.