That picture is most certainly
not a 2010 prototype and looks very little like the 2010 will look. Hard for the 2010 to be smaller than the current S197, when it will share the same chassis and greenhouse (roof and all window glass). There will be new sheetmetal and new front and rear fascias, so they
could shorten the front and rear overhangs if they really wanted to make the overall length shorter. I doubt they will do even that, as the current proportioning is good.
The big mystery is the size and horsepower of the engines that will be available in the 2010 Mustangs. Now that GM has announced a 300hp V6 standard in its base Camaro LS model and 6.2L LS3 422hp SS model (with 6-speed manual
trans), will Ford try to match up or go the other way with smaller and more fuel efficient engines? The 425hp Challenger SRT8 is around $40K. Nobody knows how much the 422hp SS Camaro will be, but to get it with leather seats, the premium stereo, HIDs with integral halo rings, and 20" rims (and who
wouldn't want those things?) you will have to order both the SS2 option package
and the RS option package (plus one of the separate stripe options) - which
won't be cheap. Ford willl not want to match the Camaro SS if a 400+hp Mustang GT will cost near $40K. Who would buy a 400hp GT for $40K when the 500hp GT500 isn't that much more? 340hp twin-turbo Ecoboost V6 and 5.0L V8 engines are likely for the Mustang, but neither will make 400hp. Ford will probably continue to be underpowered versus the competition but a better value.