I've been there with my own car but I cannot recommend you to do the same. Traffic is hell in the centre. Either you get there by train or plane or you leave your car in the outskirt and take the public transport.
I drove to brussels. This picture is from me driving to Belgiam, another time in winter, 2000. This is on the Belgian AutoRoute.
Walk, you can see a lot in the downtown area by walking. We never ventured out of that area though (for fear of getting lost)
HERE I SHALL GIVE YOU SOME NAMES AND TELEPHONE NUMBERS IN CASE OF EMERGENCY.......
Touring Secours tel. 233 22 11
RACB tel. 736 59 59
V.A.B. tel. 219 28 80