After the 1954 running, work began on entirely revamping the circuit. New facilities were built and a new corner, the Parabolica, was built right before the pits. Extra track used for a short course was eliminated. The biggest change was the construction of the new Monza banking. Built on top of where the almost flat, narrow original banking was, these huge concrete bankings, called the "sopraelevata" curves, were built in the same shape as the original banking had been. The only significant difference was that the "Curva Sud" was moved slightly to the north. This course was combined with the road course for the 1955 event, which was won by Fangio and was the last race contested by a full-fledged Mercedes factory effort in Formula One until 2010. The 10 km Monza circuit was now so fast that F1 cars were averaging 135+ mph per lap- though rather unremarkable by today's standards, these average speeds were even faster than the Indianapolis Speedway oval in the United States. 1956 saw an exciting race, with championship contenders Fangio, Briton Peter Collins (both in Ferraris) and Frenchman Jean Behra in a Maserati fight over the win. Stirling Moss was already out of championship contention; and Fangio retired with a broken steering arm. The Ferrari team called for Italian Luigi Musso to hand his car over to Fangio. Musso ignored the order so Collins came in and handed his car and his championship chances to Fangio. Behra had retired early with a magneto problem in his own car and took over his teammate Umberto Maglioli's car; but he retired that car, too. Musso ended up leading after Moss ran out of fuel coming through Vialone. Moss was able to refuel his car and storm off after Musso and eventually the Italian retired with steering problems, and Moss, with Fangio catching him up fast, stormed round the track to take victory. Fangio took second and his fourth Drivers' Championship.