For €5,500, I reckon your best bet would be the personal loan from Tesco, but as Clubman says, shop around. Couple of things to note in relation to a car loan:
New cars and more expensive used cars qualify for the better rates (these are usually the ones advertised)
Some places won't give you a car loan if the term of the loan and the age of the car are more than x years (7 in the case of ptsb I think, i.e. if car is 3 years old, max term on loan is 4 years).
I don't think you qualify for car finance if you are buying privately (I have just bought a new (used) car and the dealer had to be a member of SIMI and I had to produce an invoice for the lender.
In the Banking etc. thread, techman has mentioned an NIB rate of 6.2% for personal loans, seems too good to be true, but worth checking out.