Although this topic has been beaten to death on MBworld, I'll contribute my .02 about E55 vs E63

• AMG themselves stated at one of their events that the E55 is actually quicker/faster on the quarter mile and even ran them against eachother and the E55 came out ahead.
• On the dyno, the E55 is closer to 500 crank hp. E55's and E63's dyno numbers are very close meaning they have the same hp. The difference comes in the huge torque advantage of the E55.
• The transmission of the 63, although having 2 more gears, is still not geared any better than a 55 so there is no advantage there.
• The quickest E55 times on the 1/4 mile have been at 11.85. The quickest E63 times on the 1/4 mile so far have only been at 12.50 (I think?).
• The E63 has a more aggressive looking front end, updated tail lights, nice throaty V8 growl, rear lip spoiler, and a few more minor cosmetic changes that look great.
• If you want to mod the E63, most you can do is headers, exhaust, and ECU. It is a relatively new car so not much has been done yet, but it is a high compression motor and the 7 speed tranny is not rated for high torque (more than 560tq or so could mean trouble). The E55's are made to mod. Pulleys, ECU, throttle body, headers and exhaust can add way over 100bhp.
• The E55's are notorious for heat soak. Some have pump failures where the supercharger shuts down. Others run perfect. The E63's have no problems since they are naturally aspirated. So temperature plays a big factor and is a definite weakness that the E55 has.
• E63's are new, E55's aren't in production anymore. You can't get a new one.

I think that covers just about everything

 

I didn't say 5k miles. I said 10-20k miles, which, IMHO, is when a motor is just really starting to get broken in.

Forget dynos. Since we're dealing with roll-on racing here, lets use real 60-130mph measurements of German cars from an unbiased, 3rd party source (Car & Driver magazine):

2005 Porsche Boxster S (new / 40k miles)
0-60mph - 5.1s / 5.2s
1/4 mile - 13.6@102mph / 13.6@103mph
60-130mph - 19.2s / 18.7s (0.5s quicker after 40k miles)

2005 Porsche Cayenne S (new / 40k miles)
0-60mph - 6.6s / 6.6s
1/4 mile - 15.0s@93mph / 15.0s@93mph
60-130mph - 35.8s / 34.1s (1.7s quicker after 40k miles)

2003 BMW Z4 3.0i (new / 40k miles)
0-60mph - 6.0s / 5.6s
1/4 mile - 14.7s@96mph / 14.3s@98mph
60-130mph - 25.8s / 24.6s (1.2s quicker after 40k miles)

And, just for laughs, here's the data for an alternate supercharged V8 powered sedan:

2004 Jaguar XJR (new / 40k miles)
0-60mph - 4.8s / 4.7s
1/4 mile - 13.4@105mph / 13.2@107mph
60-130mph - 18.8s / 16.0s (2.8s quicker after 40k miles)

How many miles were on the '04 E55 when it raced the new '07 E63 in those videos?