Was looking for TF wallpapers for my PSP when I found these - real life vehicles modeled as TFs:
Aerialbot - Fireflight
Aerialbot - Skydive
Aerialbot - Slingshot
Astrotrain - Train mode
Astrotrain - Plane mode
Blitzwing - Plane mode
Blitzwing - Tank mode
Megatron - Tank mode
Optimus Prime
Prowl
Ratchet
Skywarp
Starscream - "This should how Screamer have looked like in the 07 Movie and not like a chicken!"
Stunticon - Breakdown
Stunticon - Dead End
Stuncticon - Dragstrip
Stunticon - Motormaster
P.S: Images have been compressed. If you want to download the larger version, please click here