Thanks for all the views above, rules of thumb are useful but totally agree depreciation rates vary hugely depending on so many variables. So not much use if choosing between cars to buy.

That's why what I'm really after is recommendations for a website where they have a good depreciation tool, based on past data from the UK market.

There is a really good one called CarEdge.com for the US market which is awesome as it shows you the likely depreciation on a graph and let's you change lots of variables including how old the car was when you bought it. Does anyone know of a similar website for the UK market?

I've found a few but none with graphs, and the level of functionality that CarEdge does.

So a £20000 new car will be worth:

• £16000 when it has left the showroom and driven a few hundred miles
• £12000 at a year old
• £9000 at 2 years old
• £6750 at 3 years old

All those figures (except perhaps the first one - See below) are total nonsense.

Take the Superb we have just changed. 3 years 8 months ago we paid just over £19000 (via a broker) for the brand new car. For the record the full list was about £22,000. At those 3 years 8 months we got £11,000 against a very heavily discounted (over £5000 off), pre reg cancelled order (8 miles 3 weeks old) Skoda Superb iV, it was not like the dealer was selling me a car he still had loads of profit in.

Bottom line is there is no hard fast rule since all cars depreciate at a different rate which depends on so many factors its pretty much impossible to forecast.

If you want low depreciation buy a £6000 Dacia, you will never loose more than £6000 regardless of how long you keep it.

Indeed - the likely depreciation many motoring websites give is always based on the manufacturer's list price, and who (other than people buying top-spec executive and sports cars) pays list price any more these days?

Add to that what cars are 'in fashion' today may not be in a few years - diesels being the obvious example.

As you say, buying a cheap car means you may lose quite a bit in percentage terms, but in cash terms it's still far less than a car twice the price to start with that depreciates by 10 or even 20% less - and that's if you flog it after 3 years. The longer we keep it, the lower the depreciation on cheaper cars (whether list price or a negotiated one).

When I bought my (essentially new - only 15 miles on the clock) Mazda3 back in early 2006 for £10.3k, it essentially didn't depreciate for about 1.5 - 2 years by the HJ calculator. Today it's probably worth around the £1k (possibly less), but coming up to 15yo it means it depreciated by only an average of £620pa.

I was lucky on that score this time, whereas my previous 90s Micra depreciated by an average of £780pa over the previous 8 years before PXing it for the Mazda (and without taking inflation into account).