Megatron's vehicle mode is the car seen on the larger toy, mainly moulded in dark grey but with some orange used on the robot limbs and with some purple paint. A passable plane mode can also be formed from this toy, but isn't an official mode.
TF to robot mode: pull the back wheels out to the sides. Fold the waist piece back and straighten the legs behind the car. Fold the feet down so they point downward and the soles face out the back of the car. Pull the front wheels out to the sides - mine has snapped one of the pegs that hold the wheels & housing in place doing this ! - and fold them back onto the top of the back of the car. Separate the front of the car and fold each half out to the sides. Fold the driver's compartment down under the car to form the robot's chest and reveal the head. Turn the arms in so the elbow faces down, then bend the halves of the front of the car down to fold up the hands.
Megatron is a great reduction of the leader toy with ball jointed knees, hips and biceps. If you can shrink the larger toy so successfully, then does that hint that there's not enough to the larger toy ?
Megatron with a new (better) grey paint scheme. Nice, get it.
There's also a very similar version of Galvatron in the EZ Collection which figure which was given away free with an issue of Dengeki Hobby Magazine in Japan. See Remy's Collection 380: EZ Collection Galvatron for pictures