Although I read somewhere that the accident rate in Belgium was one of the highest in Europe, we managed to make it out unscathed. Some thoughts if you are considering renting a car:
-invest in a map, we bought the Michelin Benelux map from Amazon for about $10US and though a little unwieldy to use in the car, found it invaluable in planning a route and when road construction led us off our path.
-if you are comfortable driving a manual, rent a diesel car if possible, diesel is much cheaper than unleaded gas.
-automatic cars are almost non existent in Europe and are much more expensive to rent. We ended up with one for the same cost as a manual when we remarked that the compact manual car seemed too big
-rent as small of a car as you can, streets are narrow, gas is expensive and parking tight
-the major roads in Belgium are mostly in excellent condition and extremely well marked with destinations, much more so than the US
Belgium is one the easiest countries in the world to travel in. This is largely the result of an excellent network of railroads. The trains, operater by SNCB, run frequently between all major destinations. They are also very clean and modern. There several passes available for tourists that are not outlandishly expensive either. Probably the best if you are spending a week or more in Belgium is the Rail Pass which gets you 10 station to station trips for 68 Euros for 2nd class and 104 Euros for 1st class. There are also discounted tickets for weekend trips, for those under 26 years old and of course there are senior discounts too. If you are going to spending alot of time on the rails in the Benelux countries then I might recommend that you purchase a Benelux TourRail Pass. They will allow you to use the rail network in all of the Benelux countries for five days over a period of a month. Because I was traveling quite extensively over these countries I actually bought two such passes. They cost $217 for first class and $155 for second class.