1989
Turbocharged engines banned completely,[24] normally aspirated engines of 3500 cc in size and 8 to 12 cylinders the only engines permitted, fuel restrictions removed, all track side guard rails must be a minimum of 1 metre in height and the pit wall must be a minimum of 1 m 35 cm in height, all drivers subject to anti doping testing as per IOC guidelines.[25]
1990
Large mirrors and quick release steering wheel made mandatory, all marshals and medical staff must practice driver extrication exercises.[37]
1991
Front wing narrowed from 150 cm (59 in) to 140 cm (55 in). Rear overhang reduced from 60 cm (24 in) to 50 cm (20 in). More stringent testing of survival cell by FIA including seat belts, fuel tanks and rollbar. Points scoring system overhauled, win now secures 10 points and all results to count instead of best 11 scores.[37]
1992
Yet more exhaustive testing of survival cell including rear impact testing, height of kerbing lowered, minimum width of pit lane increased to 12 m (39 ft), pit lane entry chicane mandatory, safety car introduced.[37]
1993
Rear tyre width reduced from 18 inches to 15 inches to reduce the grip and so the speed of the cars, overall car width reduced to 200 cm. Rear wing height reduced from 100 cm to 90 cm, distance of front end plates from flat bottom increased from 25 to 40 mm (0.98 to 1.57 in),[37] head rest area increased from 80 to 400 cm2 (12 to 62 sq in). Continuously variable transmission (CVT) banned before ever appearing at a race.[38] End of race crowd control measures implemented, 50 km/h speed lane restriction during free practice. Fuel used restricted to that available to the general public.[39]
1994
Ban on electronic driver aids such as active suspension,[31] traction control,[33] launch control, ABS, and (without ever appearing in a race) 4 wheel steering[40] at the beginning of the season, mid race refueling allowed for the first time since 1983,[41] post Imola sweeping changes introduced to slow cars down, starting from the Monaco race onwards, a pit lane speed limit is put in place; between the Spanish Grand Prix and the German Grand Prix, additional changes are phased in and include a reduction in the height of the rear wing of 10 cm, an increase in the height of the front wing, no front wing trailing assemblies to extend behind front wheel, a 10 mm wooden plank fitted to the under tray (permitted to be worn by no more than 1 mm by the race end), a ban on high rear wing assemblies extending ahead of the rear axle line to sidestep the wing height restrictions, depressurising the engine airbox to reduce power, minimum headrest thickness 75 mm (3.0 in) introduced, more stringent fire extinguisher regulations and driver helmet criteria implemented, a pit lane speed restriction of 80 km/h (50 mph) in practice and 120 km/h (75 mph) in race conditions introduced, also the parade lap was to be completed behind safety car (abandoned from Imola onwards), pit spectator area to be fire shielded, 27 corners identified as very high risk and as a result changes to circuit layouts implemented to remove or modify these parts of the track. After Imola, pit lane speed limit is implemented.[37]
