I have to say I agree with
@Tfp but was reluctant to butt in myself and say an open auction may not be a good idea.
It was with that in mind that I suggested the better pictures to help it along.
It’s not to say you won’t get a good price but I think it’s a significant risk. How are you going to feel if you only get 1 bid at the opening position?
Personally I’d never sell a car on open auction - particularly one that nice. Autotrader or eBay classifieds sounds like good advice to me.
I also like Gumtree but I know a lot of people hate it with a passion.