It's not unreasonable but it's a tricky one and all depends around usage, and what you want to drive.
There are so many new cars registered in the UK, we're addicted it seems to getting new cars. The majority of these of course are bought on finance - nothing wrong with that if you can afford it! People like buying new because you can choose the spec, there's the safety aspect (perceptions that safety improves every year on new cars) and the image thing.
Depreciation is the scariest part, but then again if you're leasing a car for £150 a month, or you buy a used car at £800 but then get hit with a £900 bill, who's saving money?
A bit about me - I work in London and so I only drive at weekends. I have a 16 year old Jaguar which cost me £1400. It drinks petrol but I use it for an hour or two each weekend as my partner has the sensible Toyota for DD (£4400, £30 tax, £320 insurance). I keep my car on classic insurance which costs me £110 a year. I always wanted it, I'm mad I know.
The point is, I think there's many ways to skin this cat, and people will insist on new cars because they'll quote the maths and stats that shows they're cheaper and safer.