The Ligier JS31 was a Formula One car designed by Michel Tétu and Michel Beaujon for the Ligier team for use in the 1988 Formula One season. It was powered by the new, normally aspirated, 3.5L Judd CV V8 engine and, like the rest of the F1 grid in 1988, ran on Goodyear tyres. Drivers for the team were French veteran René Arnoux in his 3rd season driving for team boss Guy Ligier, and Swede Stefan Johansson who had finished 5th in the World Championship with Ferrari in 1986 and 6th with McLaren in 1987.
The JS31 was the first non-turbo car produced by Ligier since the Cosworth DFV powered JS21 used in the 1983 season, and it proved to be very uncompetitive despite the best efforts of the team and its experienced drivers. The car's major failure was a lack of downforce with Johansson in particular reporting several times during a frustrating season that he had to drive the car as if on a wet track because it had so little grip and this was reflected in the car's results. Johansson, a frequent podium visitor in the previous three seasons, failed to qualify six times and never finished above 9th while seven time grand prix winner Arnoux failed to qualify twice (San Marino and France) and never finished a race higher than 10th. Neither driver qualified for the San Marino Grand Prix, the first time in team history that neither Ligier made the grid.
The French Grand Prix at Paul Ricard proved to be the lowest point of the season for the French team. On the eve of Arnoux's 40th birthday (celebrated the day after the race), neither Arnoux nor Johansson qualified for the team's home Grand Prix, something that did not please the team's owner Guy Ligier, though as one team member pointed out thankfully he was not actually at Paul Ricard that weekend.
Ligier did not score a point during 1988, their worst season since 1983, when they also failed to score. On several occasions both Johansson and Arnoux struggled to outqualify 1987 Formula 3000 champion Stefano Modena and sportscar driver, 33-year-old Argentine Oscar Larrauri (an F1 rookie) in the equally uncompetitive EuroBrun (the EuroBrun team were F1 'rookies' in 1988, though Modena, who had made his debut with Brabham in 1987, was seen at that stage as a future star of the sport...if he could get a competitive drive). In an effort to optimise the weight distribution of the car, it was designed with an unusual and heavy arrangement of fuel tanks: there were two cells either side of the driver, another between the driver and the engine and a fourth between the engine and gearbox.
Ligier only had both cars qualify for a race on 10 occasions in 1988. On 5 of those occasions both cars failed to finish.
The JS31 was replaced for 1989 by the Ligier JS33.