Originally Posted by m4a1mustang

If you are used to driving automatics and now drive a manual transmission, those autos probably feel a lot more frisky off the line in regular driving than your manual transmission car does. Why? Because with the MT you have to consciously operate the clutch and gas pedal simultaneously to get moving. Unless you're purposely launching they it's a little slow to get a quick getaway. With the automatics, they just feel like they are ready to get up and go since all you've got to do is give it gas.

I feel this way when I drive my girlfriend's CLK500. In regular driving it feels much peppier off the line than my Z did and my 5.0 does.

Also, as has been documented here before, some people have experienced a severe throttle input lag under 4k (the car feels like it bogs down and just about dies when you give it throttle), so it's possible the OP could be experiencing something like that.