Hi, I used to have a 2003 Sedan and now I have a 2003 coupe. When I bought the coupe I still had the sedan and thought the sedan's tires were MUCH quieter than the coupe's tires....so I switched them around. To my surprise, the noise level stayed the same...the coupe was still much louder. So I figured that maybe I had a bad wheel bearing. Upon inspecting the wheel bearings, they all seem FLAWLESS. ZERO wiggle, ZERO scraping noises when turning them, nothing!

So my question is...is the sedan's interior simply quieter than the coupe's?

 

You probably have the imfamous front tire feathering issue that afflicts many 03-04 Zs, 03-04 coupes, and many lowered 03-04 sedans. The only real ways to address this is to cross-rotate the front tires every 2K miles, set the front toe to max toe-in (0.16"), and stick with non-directional tires. Unfortunately, these are just ways to slow the feathering issue down. It will always be there.

 

Hard to say, a lot depends on the roads encountered. I had a 95 Jeep and my kid got real sick and we had to go to Seattle. The Jeep had a running issue that showed up as soon as I climbed in so we hijacked a Cad from my brother in law. What was odd was how quiet the Cad was on the roads leading to the freeway compared to the Jeep, but how noisy it was on the freeway compared to the Jeep. I figured much of this was pavement related to the different types of tires as well as ground clearance.

I find my 2008 XS somewhat the same as the Cad, quieter on some roads, noisier on others than my other car which is a 300M with aftermarket wheels and tires (19" Toyos).

 

I guess maybe alignment is maybe the problem? Because both cars have the same suspension and they were both running the exact same tires ( I rotated the tires between the two cars ). Maybe I'll check that out.