HMRC rate is 45p a mile.

Double that for short journeys when wear and fuel usage are highest.

Indeed, as my circumstances (see the 'generation of cars' thread) show - I've done only 5-6k miles pa, but predominantly made up of longer journeys that my cars have always sufficiently warmed up and been driven on faster flowing roads, and (at least for my current car) the pence per mile figure is over 60p.

I've noticed that my car has had more issues with the brakes (binding, uneven wear) when I've been unemployed or commuting by train (and thus doing very low mileage and seldom using the car) than when I did nearer to the 10k pa mark using it at least 5 days a week for a decent length commute, etc. The insurance barely budged even when I was insuring it for essentially twice as many miles - increasing by maybe 10-15% (£30 - £40pa), so other than fuel costs, the rest were the same.

My parents do a low annual mileage in their 1.25L Fiestas over the years, but its predominantly made up of journeys under 5 miles on urban roads, and they have lots of issues associated with uneven tyre wear and wear of suspension parts, often due to them going over speed humps a lot or just poorly surfaced roads. Of course, despite their car being smaller and in theory, more economical than mine, I think they only get an mpg in the late 30s on average, whereas I get 40-41 in my larger Mazda3 1.6 (both N/A petrols).

You've bought it, taxed it, insured it, MOT and service so why not use it? Or is it sat on the drive to admire! Do you drive it in the rain? The less you drive it the greater the cost per mile!

It depends on the type and frequency of the journeys taken - lots of very short urban trips from cold are bad for cars (more so for modern diesels).

Better to do what I do - to keep the battery topped up and to give it a good run out, I drive to a nearish town (12 miles away) along the local dual carriageway once every 3 weeks in the summer, every 2 in autumn/early spring and once a week in winter - to do my grocery shopping. The in-between weeks I walk to my local supermarket, getting a decent amount of exercise.

Same mileage as doing my weekly shop locally by driving, and far better for the car and far better mpg (+20% over urban only). Overall cost is lower too.

The less you drive it the greater the cost per mile!

So drive it as much as possible just to reduce the cost per mile? That's a cockeyed argument :-(

A truly pointless question except to say a large powerful newer car will cost more than small cheap.

As an accountant when asked "how much does it cost" the answer could alway be how much do you want it to cost".

Fundamentally the answer depends on why you need to know. In summary coetc sts are short term (petrol etc) annual (service and MoT etc), irregular (tyres, repairs) etc) long term (depreciation).