There are big parkings located next to a couple of big subway stations.
If you really don't have any other option, you can take the car. There are big parkings located next to a couple of big subway stations close to the highway R0 (like Parking C at Heysel). From there, you can walk or take the subway to the festival.
We were also offering parking spaces next to the festival site at € 13 per day, but these are now all sold-out. If you bought a 1 day parking ticket, your car can stay on this parking until 4AM in the morning. If you bought a parking ticket for all 3 days, your can stay until Monday morning 4h00. At this time we are obliged to close the parking.
This parking P2 is only accessible via the Atomium Avenue (follow the signs). Attention: the Bouvelard du Centenaire will be inaccessible between the Louis Steens roundabout and the Atomium.