Born in Moorlage, Germany, Heeks was a very talented driver who drove a Formula 2 AFM 49-2 on German tracks and hillclimbs. This car was originally built for Emil Vorster with an 750cc supercharged Fiat-based AFM engine installed, but was then upgraded to Formula 2 specs by fitting a 2-litre BMW engine. This AFM was the last of the monoposto series.
He scored wins with the car in 1950 in the Maipokalrennen at Hockenheim and at Dessau. He then had a new AFM 50-8 built using spare parts from AFM 49-2.
In 1951 his best placing was third at the Nurburgring in the Eifelrennen.
He drove his AFM-BMW in the 1952 German Grand Prix and qualified a very respectable 9th. Unfortunately his race ended in retirement on lap 7 of the 18 lap race. He also finished second at the Sachsenring and 4th at the Circuit de Cadours, near Toulouse in France, in a rare appearance outside Germany. He finished 6th in the West German Championship.
By 1953, the AFM was no longer competitive and Willi joined the ranks of the Veritas runners, although most of his major races ended in retirement. He did cause something of a stir in the German GP when his Veritas Meteor led the Ferrari of Rosier before eventually breaking down on lap 8. He made the trip to race in the GP des Frontières at Chimay in May but once again failed to finish.
He subsequently drove a Mercedes 220S with Erwin Bauer in the Nurburgring 1000 Km in 1956 and a Porsche 356 S75 in the Internationales Solitude-Rennen at Solitude in 1962.