It can be done with a personal loan, but the regs say only one car loan for a car because of the legal issues if you default on a loan - if you have two loans on one item, then it becomes very muddy who then owns it.
The company car loan is the best rate, but you won't get much for it, and a lot of people buy new because checking the service and accident history is not as easy, the heat and dust degrade cars quickly and a lot of cars are abused or neglected. Most of the garage staff are shockingly bad at their jobs; there's no way I'd trust them with any significant repairs.