Si4 Depreciation in the UK

Mark, it is also regionally important. You will get a far better valuation on a petrol engined SUV down in the south east of the UK than you will in the more rural areas. In London there are far more sales of petrol engined Land Rovers than in the rest of the country. When I had a petrol engined Disco1 my local dealer even sent me to a London dealer they were connected to to sell it to when I wanted to change to a diesel D2.
The reason for this regional disparity is that Diesel engines, and especially now they have DPFs, are as economical in stop start city driving as a petrol engined equivalent, people don't realise that Diesel engines are at their most economical when running at steady rpm over distance and once fully warmed up, any economy over a petrol engined car disappears in city stop/start motoring. So if you live outside the SE of England where there is less traffic diesels hold their value better than petrol engined SUVs. Land Rover aside, their is also the fact that most manufacturers still make diesel engined versions of their cars more expensive to purchase than the petrol engined versions.
Yesterday on the run round Birmingham on the elevated section of the M6 sat between 35 and 50 in the road works my average trip mpg got up to 48mpg( the best I have ever seen in my Evoque) as soon as I got into stop start crawling it tumbled back to 28mpg. I was surprised also how quickly, once clear of all the stop start crawling the fuel consumption returned to above 40mpg although an hour sat at 80+ soon got it back down to 35!