If it's worn then you need leather restorer from a pro outlet, it's hard work and requires great patience so may well be better taking it into a specialist.
Autoglym Leather Cleaner spray and Leather feed (in that order) are best used to keep undamaged leather in good condition for years if used every few months.
Not shiny enough until you can see yourself!
http://robbiekhan.co.uk/root/photos/cars-mine/e46_coupe/wash_side_cornerreflection_2.jpg
http://robbiekhan.co.uk/root/photos/cars-mine/e46_coupe/wash_side_shiny_shoes.jpg
Had the Nilfisk a long time now and i's been a joy to use, still packs its original punch and still in robust condition considering it's been left out in the shed the last few months so has seen through many cold nights but gets used every week at least twice.
It is better quality than any Karcher under £100 too (a relative got a Karcher on offer recently and the Nilfisk is much better for performance and quality).
Wow i'm checking on screwfix and it seems they've upped the price of these! must have been getting a lot of demand.
I'm sure i paid £100 for the pressure washer with accessories and now its £129.99
How are you finding the Nilfisk to be? Been thinking of getting one as they seem to be priced quiet well.