Being into classic cars one thing that struck me when we first moved to Orce was the amount of older cars on the road. Not only on the road but in good condition, Fiat 124's, Ford Cortinas and escorts, the kind of car your are only likely to see in a scrap yard or in the hands of an enthusiast back in the UK.
Spain in general has very low humidity and up in the sierras even less so, you will also find no salt on the roads in the winter. This results in very little rust... Cars also tend to be in general, low mileage. Sometimes Huescar to Orce (17 km) can be a treck for some! Looking through the ads it is quite common to find a 20 year old car with less than 100k on the clock - and thats km. However prices of second hand cars in the area are high, this does appear to be relevant though, with particular reference to classics a good example of an old ford will be 1000 pounds in the UK over here expect an asking price of 6000 euros.
Fuel also makes a big difference in a cars selling price, petrol models tend to be around 5 - 10% less that their deisel counter parts which command a higher value due to deisel being significantly cheaper at the pump.
Are you bringing your UK car to Spain for good? I have always been a believer in that if you are not concerned about driving a RHD car in Spain then do it - even spending 600 - 900 euros on an ITV and plate change, to buy the equivilent left hooker here in rural Spain will be more expensive.
As for classics...mine comes out on the occasional Sunday for a blast down to Maria market, or maybe a calm drive on the road thats runs along side the airstrip...
Big thanks to Mike and the guys at www.cuevapedro.co.uk for bringing over the starter motor! (parts are a problem...)