To limit power, all forced induction cars were fitted with a 34 mm diameter air restrictor before the turbocharger inlet, limiting the air flow to about 10 cubic meters per minute. The restriction was intended to limit power output to 300 hp although some WRC engines were believed to produce around 330–340 hp.[citation needed] Engine development did not focus on peak power output but towards producing a very wide powerband (or power curve). Typically, power output in excess of 300 hp was available from 3000 rpm to the 7500 rpm maximum, with a peak of 330–340 hp at around 5500 rpm. At 2000 rpm (the engine idle speed in "stage" mode) power output was slightly above 200 hp.[3]
These events were road races in all but name, but in Italy such races were still allowed, and the Mille Miglia continued until a serious accident in 1957 caused it to be banned.[43] Meanwhile, in 1981, the Tour de France was revived by the Automobile-Club de Nice as a different kind of rally, based primarily on a series of races at circuits and hillclimbs around the country.[44] It was successful for a while and continued until 1986. It spawned similar events in a few other countries, but none survive.
Initially, most of the major postwar rallies were fairly gentlemanly, but the organisers of the French Alpine and the Liège (which moved its turning point from Rome into Yugoslavia in 1956) straight away set difficult time schedules: the Automobile Club de Marseille et Provence laid on a long tough route over a succession of rugged passes, stated that cars would have to be driven flat out from start to finish, and gave a coveted Coupe des Alpes ("Alpine Cup") to anyone achieving an unpenalised run;[37] while Belgium's Royal Motor Union made clear no car was expected to finish the Liège unpenalised – when one did (1951 winner Johnny Claes in a Jaguar XK120) they tightened the timing to make sure it never happened again.[38] These two events became the ones for "the men" to do. The Monte, because of its glamour, got the media coverage and the biggest entries (and in snowy years was also a genuine challenge); while the Acropolis took advantage of Greece's appalling roads to become a truly tough event.[39] In 1956 came Corsica's Tour de Corse, 24 hours of virtually non-stop flat out driving on some of the narrowest and twistiest mountain roads on the planet – the first major rally to be won by a woman, Belgium's Gilberte Thirion, in a Renault Dauphine.[40][unreliable source?]

1968 brought the first of a series of British-organised intercontinental rallies, the Daily Express London-Sydney Marathon, which attracted over 100 crews including a number of works teams and top drivers; it was won by the Hillman Hunter of Andrew Cowan/Brian Coyle/Colin Malkin.[56] Not to be outdone, the rival Daily Mirror sponsored in 1970 the London-Mexico World Cup Rally, linking the stadia of two successive football World Cups, on a route that crossed Europe to Bulgaria and back before shipping out from Lisbon to Rio de Janeiro, after looping around South America, and a run through some of the most frightening sections of Peru's road race, the Caminos del Inca, they wrap it up being shipped to Panama and a final run up Central America. The Ford Escort of Hannu Mikkola and Gunnar Palm won.[57] These were followed in 1974 by the London-Sahara-Munich World Cup Rally,[58] and in 1977 by the Singapore Airlines London-Sydney Rally.[59]