Crossfire comes with 3.25:1 Axle Ratio, except the SRT-6, which is 3.07:1.
http://www.chrysler.com
"A numerically lower axle ratio results in lower engine rpm and better fuel economy. A numerically higher ratio improves acceleration, climbing grades, carrying loads or pulling a trailer."

2003 SLK320 Roadster (essentially our car) 3.27:1.
2003 SLK32AMG Roadster (essentially SRT-6) 3.07:1.
2005 CLK320 Coupe (same 3.2L engine) comes with 3.27:1.
2005 CLK320 Cabriolet (same 3.2L engine, same "TouchShift" 5 speed auto) comes with 3.45:1 rear.
2005 SLK350 Roadster will supposedly have 3.27:1.