Darth Vader recording for Tom-Tom GPS

It's pretty funny to see Darth Vader getting fussy with an audio engineer, but I don't really get why Vader comes across as such an idiot. I mean, he spends like twenty minutes trying to master how to say "roundabout."

Normally I'm pretty good at recognizing celebrity voices, but in this case I just can't tell if that's James Earl Jones or not. It doesn't sound exactly like him, but if it's an impersonator, he's doing a very, very good job.

Yoda did one of these things too. Kind of a diva, he is.