You will always struggle to keep a black car looking clean.
But that doesn't mean you can't make things a bit easier for yourself. If you deep-clean the bodywork and get it as smooth as possible before topping it off with a decent wax or sealant then it will be so much easier to wash because the dirt will fall away. i.e. 30mins for a shampoo and rinse instead of an hour because you had to keep going over all the panels with the wash mitt 2 or 3 times before the dirt was gone.
So what to use? There are as many different opinions on that as there are members on here . . .
But here's what I (generally) use:
For that twice-a-year deep clean: 2 bucket wash with Meguires NXT shampoo. De-tar with Tardis or AutoGlym tar remover. Clay bar the bodywork so the surface feels "glass" smooth. Polish with Poorboys Blackhole. Finish with AutoGlym HD wax. Wheels also clayed, polished and sealed with a wheel sealant. This all takes a good few hours to do properly.
But the trade-off is the Once-a-Fortnight washes don't take long at all - Quick hose-down (if you've sealed your wheels correctly they will be 98% clean after hosing down), 2-bucket wash with the NXT shampoo, rinse with an open-ended hose (most of the water will run off this way), spray each panel sparingly with AutoGlym Aqua Wax (whilst still wet) then use a microfibre to dry the car and spread the wax at the same time. Finally buff up each panel with a clean microfibre.
The aqua wax tops up the surface very well indeed but can work out expensive over the year unless you buy the 5-litre tub (e-bay). Result is you'll have a deep, shiny car most of the year with a good protective wax covering on it which will bead beautifully in the wet.
Last edited by Bezste; 30-01-15 at 11:10.