If we took Hania out of the equation I'd say it was a young local who took the car for joyriding or chopping. He'd have to know about the trailer park and frankly, the car doesn't sound like a big prize compared to a Mercedes or Range Rover. It's old and the paint is peeling so it has little value by itself.
But once you add Hania back in the whole scenario changes and it starts to seem like a targeted abduction rather than a carjacking.
Why did the perp steal the car? Best guess it was for a quick getaway in a vehicle that couldn't be traced back to him. If he had his own vehicle stashed nearby then the aunt's car would have been found by now. At the same time he took quite a risk in knowing a witness saw the abduction so exactly how long would he be comfortable driving a car reported as stolen?
I'm really surprised the car hasn't been found by now. Ugh, I'm at a dead end. For all we know - speculation only! - it was some guy high on meth. I hope LE has more going on than we know! Each day that passes makes it more dangerous for Hania.
MOO.