Still be a massive ballon payment at the end!
75k of finance (90k less 15k deposit), £444 a month, interest free is 169months for a complete capital buy lol.
Much more likley a 24-48month deal where you walk or buy. Let's say 36 months at £444 is 16k. So if you walk after 3years thats 31k gone, ouch! that was no interest on there too so call it 35k for ease.
3yr old Aston looking like 60k ish, so about the same as the depreciation so the deals about right.
What ever way you look at it though, big pockets are needed.