In some episodes MacGyver did drive some odd cars ~ like a station wagon in one show that was just on TV today, that would have been a current model at that time...
And as well , in the last couple of series there were a couple of episodes where he can be seen getting out of cars like a Chev Nova, and a Ford Taurus (or similar..) ~ I reckon they could be either hire-cars or cars from the Phoenix Foundation car pool, depending on the particular story lines..
I only considered the pickup, the Jeep and the classic wagon ~ along with his motorbike ~ as being the
real "MacGyver vehicles". And the rest as ring-ins, second-stringers and one-offs..
Just one more reason he would have needed a decent sized garage/workshop wherever he might be living...