to do such an underglows you must do some rectangular shapes(on a new layer) ,then fill them with a colour.then on the blending options you check the outer glow where you put the same colour....
LOLZ bravo Madskillz !!!
Phillip what you've done there is not Virtual Tuning is just a simple photo chop (excepting the doors and neons ...i think that's your own work) the whole front end and side skirt is copyed from the same car ...i dont see much of your work in that !?
Think on that , maybe the next one will be more original ! Good luck !!!