That is great advice - I'll have to remember that myself.
quilkin - I'm sure you already thought of this, but in case you haven't - have you considered using a vehicle mudguard? Maybe a part like the following: http://alpha.bricklink.com/pages/clone/catalogitem.page?P=98282#T=C
Yes, on the one hand, the mudguard will not allow you to get the effect of multiple bricks and colors. But on the other hand, if you use a mudguard, you won't have to worry about the gaps created by trying to recreate that arch.