Experts reckon that just by cleaning your car, you can add £100s to its value; a day's effort will be time well spent, and it shouldn’t cost the earth.
Outside
Your first step should be to clean off all the road grime, using a good-quality car shampoo. NEVER use washing-up liquid, as it actually helps promote rust, unlike car products, which keep it at bay. Work from the roof down, rinse off well, and dry with a chamois leather.
Now you need to deal with the details:
Stone chips are unsightly, can rust if not attended to, and usually put buyers off. Repair them with a touch-up stick. These are not expensive and they can dramatically improve your car’s performance
Wheels caked in brake dust look awful. On alloys, if it's particularly stubborn, buy an alloy wheel cleaner and treat them. If you've got wheel trims, consider replacing them - especially if they've been kerbed. Damaged alloys can be repaired too, but this is more expensive
Missing trim or badges stand out like a sore thumb to used buyers, so buy replacements. Breaker's yards offer a cheap source of parts
Clean less obvious parts such as sills, wheel arches and the inner panel of doors; this will impress buyers, and helps create a 'well looked-after' image
A good polish will create that 'new car' shine so many used buyers are looking for. Don't worry if paint residue appears on the cloth; this is just a layer of 'dead paint' you're removing - there'll still be plenty left on the car!
Inside
Cleaning the interior requires a little more hard work. Starting with the vacuum is always best - treat carpets, seats, dusty crevices and the dashboard itself.
Use low-gloss cleaner on dashboards – don’t use household polish
Clean the windows after the dashboard with a glass cleaner or damp chamois
Replace any non-standard parts, such as racy gear knobs or alloy pedal covers. They won't impress buyers, who'll think your car has been thrashed. Standard is always best
Holes, usually from mobile phone holders, can be filled in by specialists. They can also repair any damage to dashboards or door trims, and it doesn't cost the earth, either
Avoid dousing the car in air freshener, unless you have smoked in it - in which case, buy an odour neutraliser. Spray the ashtray too, after giving it a good clean
Lift tatty old mats out; the clean carpets underneath will look much more attractive.
Mechanicals
Car buyers love looking under the bonnet, even if they haven't got a clue what they're looking for. You should therefore make sure they like what they see.
Steam-cleaning is much-loved by car dealers, but can arouse suspicion; are you trying to hide oil leaks? By all means clean the engine bay, but don't go overboard. Don't bother with older cars, though, as steam-cleaners can sometimes damage fragile parts or connections
Oil changes are cheap, and clean oil looks far better than sludgy treacle. Make sure the oil level is correct too
Fill all water and coolant bottles up, maybe using a sweet-smelling windscreen washer?
Tidy up generally; attach alarm wiring correctly, clean out leaves from air intakes, and generally make the engine bay appear cared-for