Pre-race
An entirely new complex along the front stretch was built, housing modern pit stalls, garages, and the new observation suites built above the garages.
As for the race, the grid line-up was an unusual affair. 1991 was supposed to be the first year the World Sportscar Championship ran to the new '3.5L' rules, which meant a new breed of sports-prototypes. Although TWR-Jaguar, Mercedes-Benz and Peugeot all built cars to the new regulations for the 1991 championship series, the amount of privateer teams was low and there was simply not enough of these new cars to fill the grid. The FIA allowed the first 10 spaces on the grid to be reserved for the fastest qualifying 3.5L cars from the World Sportscar Championship, while the rest of the field was made up of older formula Group C cars. In another twist, some teams which had 3.5L cars, but entered previous year's championships with Group C cars, were allowed to enter their "obsolete" but more reliable (and for Le Mans in 1991, quicker) Group C racers. In the case of TWR Jaguar and Mercedes-Benz, their 3.5L cars (the XJR-14 and C291 respectively) failed to qualify and instead they raced using their XJR-12 and C11 models. Peugeot Sport on the other hand only had their 905 model to race, with 1991 being their first full season in sportscar racing. Being the only factory team running the 3.5L formula, the French marque had the honour of starting 1st and 2nd, even though they had only set the 3rd and 8th fastest qualifying times.
Read more about this topic: 1991 24 Hours Of Le Mans