Personally, I don't think it's a good decision for the following reasons:
If I am not mistaken, a total of 5 female students from WVM currently live with MC: Jamie, Shauna, Willow, Stacy, and Elizabeth. The old car is totally unsuitable for transporting 6 people and more. All the more so when MC and Jamie are supposed to have children at some point in the future.
The car attracts quite a bit of attention, and MC and his entourage have had more than enough negative attention in the past. At first I was going to mention Ryker's boss and her other minions, who could use the car to keep an eye on MC, but then I realized that's absolutely unnecessary: He's already generated so much attention that her people shouldn't have any problems keeping an eye on him anyway, if they want to.
If anything then MC should consider getting a driver's license for passenger transport, since sooner or later it will come down to needing his own (mini)bus to transport everyone.