However, the race was marred by the death of a number of competitors. The co-driver and pacenote systems championed by the Mercedes teams of the previous year were vindicated by the failure of an alternative contemporary system used by some other works drivers, notably those of Lancia who in 1953 year had entered five cars; three 3.3-litre D24s for Felice Bonetto, Juan Manuel Fangio and Piero Taruffi, winner of the 1951 edition of the race, and two 3-litre versions for Giovanni Bracco and Eugenio Castellotti. During pre-race runs of the route at much safer speeds, Bonetto and Taruffi painted warning signals on the road to remind themselves of particular hazards. As the D24 was both open and single-seat, there was no co-driver. This resulted in the death of Bonetto who, leading the race under pressure from Taruffi, missed his own warning signs. Entering the village of Silao, he encountered a dip in the pavement at excessive speed and impacted a building, killing him instantly.