My advice is: Do not do it!!!! It gives a lousy result!!! Not worth the effort!!
OK then, it's brilliant. I have now done 2 coats and need one more I reckon. All with 2.5 litres of paint!
But don't you do it, I want the tidiest van.
Seriously though, this is a brilliant alternative to a spray job (for which I was told would cost at least £1200. I was told this today by a paint sprayer, he was very impressed by the progress so far, and the cost). You have to pace yourself and be aware that you have to wait for paint to harden before each flatting. My colour is more orange than I wanted, I wanted a deeper red, but the Tangoed effect is rapidly growing on me. The shading/light patches on the pics is just light reflection. There are just a couple of dark patches on each panel to paint over.
Problems:
Couldn't get the smaller high density foam rollers
Flies

Didnt rub down enough on one of the rear vent areas (previous paint had edges)

Various paint prices, I saved £20 by posting a help notice! (Honest).

Drips: Put cardboard down, or paint on a surface that doesn't matter. Another option is to wet the floor before starting.
Finally, tell people to F**k off when they say "What are you doing? You need to spray paint to get a good job, this'll be crap".

Look at pics and see for yourself!
AND: It really can be done for less than fifty quid!!!
I'll post a pic when it's all finished and rebuilt.