The suprise is the Benz not because of how it drives (not that special) but the transmission. In GT4, they have actually gone to the extent of showing the difference between an auto and manual car ( that means a car that is only available in auto in real life such as the SL55).
Theres no blip of the throttle on downshifting and when up shifting, there is no abrupt 'close-throttle' sound of that in a manual. Just a kinda follow on to the next gear like in actual autos (does that make sence). I even went into GT3 and drove the SL600 coupe which is also only available in auto and it just acted like all the other manual cars so they have changed this for GT4 which is great.