I had my 2002 coupe in the shop and the dealer provided a 2003 C coupe as a loaner. The 1.8 liter engine is definitely quieter and smoother. I also noticed a few other characteristics when comparing my 2002 to the 2003 coupe.

The 2003 coupe...
1. Suspension was much tighter and sportier than my 2002 - Seemed to handle better than my 2002
2. Wind noise was more noticable
3. Seemed more fuel efficient when pushed harder in town or on the highway
4. Seemed lighter and better balanced front/rear.

Have any of you noticed the differences in the suspensions? (e.g. with the 2003 have a better handling and slightly lower suspension?)

 

Suspension is unchanged. Was the loaner a C7 car? Your 02 isn't, correct? That would certainly explain the difference in character. There's only a 50lbs weight difference between the two cars...don't get too excited. Yeah, a smaller motor is going to use less gas. IMHO, the best things that the 03 has going for it are the Bi-Xenons.

 

...which means the difference is likely explained by tires and / or tire pressures.

 

won't a different tire with stiffer sidewalls offer a firmer ride assuming everything else is exactly the same?

 

Only cause the engine is quiter, the noise is exactly the same for both years.

 

if you figured that by your self then you are a damn smart :p
seriously

 

I was about to say that

as far as #1 goes, who knows, maybe they did tuned it a little tighter. Comparing my sis's 00 CLK320 to my bro's friend's 02 CLK320. My sis's car rides like a boat, and the 02 CLK320 does have firmer suspension and better noise insolation.

 

All cars feel firmer when new. The shocks, bushings, etc all loosen up over time. Same goes for the tires. New tires make even a car that's only a few years old feel dramatically different. The rubber gets harder, the ride gets rougher...

Ive driven both, and if you can tell the difference in engine noise level(in decibels) between the 02 and the 03, then your hearing is outstanding. My 02 is very quiet going down the road. The 03 makes less growling under accelleration, but not that much less.

 

I was comparing when I drove my sis's car when it was new to my bro's friend's car. It was never the same even when my sis's car was new.