It's always up and down with a sectors of cars depending on lots of factors (fuel costs, tax, image, time of year, supply, etc). 4x4s have taken a bigger dip in the last couple of months than other sectors but prior to this have been very strong despite all the affecting conditions. The big factors causing the recent drop are the psycologically bad £1.00 per litre looming but more so the number of used 4x4s traded in at the new September registration change. This has caused an oversupply which will fade out once the weather starts to turn to winter which is when 4x4 sales traditionally pickup.
Interestingly, early new reg figures from the trade are showing that 4x4 sales (small SUVs anyway) have been very strong this September and this bodes well for 4x4 demand - and therefore prices - once the oversupply has been mopped up over the next couple of months.
Cheers
Rog