what vehicle is megatron

According to the sources, Megatron has transformed into various vehicles throughout the Transformers franchise, but he has never taken the form of any human-made vehicle until the movie "Dark of the Moon". In the original series, Megatron transformed into a Walther P38 pistol. In the "Transformers" movie series, Megatron transforms into a Cybertronian jet plane and a monstrous racing vehicle. In the "Transformers: Age of Extinction" movie, he transforms into a silver and black Freightliner Argosy cab over trailer truck. In a YouTube video, a screen-used Megatron truck from the "Transformers" movie franchise was shown, but it is unclear which movie it was used in.