I now keep the motive mobile in his inventory and a 2nd car in the driveway, so the MM can't be parked there. Also, he had enough points for the telepad device, so I'm using that to go where I want, tell him to go home with the MM and 2 seconds later he's rested, (gotta love this car) still where I want him and ready to go. It works...
He's a level 10 singer but no stars for celebrity status.
The MM is the preferred vehicle, but clicking on it even when in the backpack doesn't mean he's going to use it. 'Go Home' seems to be the only option that doesn't bring the limo.
I had a similar problem once before with the Fire Engine WooWoo 4000. After days, I finally figured out to put it in the family inventory build/buy mode and that allowed me to use his personal car, the preferred one. Another sim got a career rewards vehicle and that went into his family inventory right away. Never used. Unfortunately, the limo is not a career rewards vehicle which he's entitled to keep. Shame.
Bear