In Age of extinction, in the scene where Optimus is on the road with Cade and Tessa (after they take refuge in the broken down gas station), he transforms into a shiny new Western Star 4900 Phantom truck just by 'scanning' a similar truck that was passing by. One should remember that Optimus was pretty beatup and in terrible condition when Cade found him initially.
So all it takes to fix a transformer is a vehicle nearby that it can 'scan' and transform into? Or is this just more Michael Bay crap?
Edit: My issue is not with the scan and transform part. Optimus was almost falling apart when Cade found him. He had bullet holes in him and he could barely stand up. Even if he did transform by scanning the truck, how did he repair himself?