The Williams FW31 is a Formula One motor racing car, designed and built by WilliamsF1. The AT&T Williams team used the FW31 to compete in the 2009 Formula One season. The car was unveiled on 19 January 2009 at the Autódromo Internacional do Algarve circuit in southern Portugal, and was first driven by the team's test driver Nico Hülkenberg. It was a mid-field runner, in contention for points on many occasions when driven by Rosberg, but rarely contending for podiums. Rosberg could have finished in third position at Marina Bay during the 2009 Singapore Grand Prix if he had not run wide on the exit of the pit lane and received a penalty.

Williams FW31
Nakajima 2009 Spain.jpg
CategoryFormula One
Designer(s)Sam Michael (Technical Director)
Ed Wood (Chief Designer)
Jon Tomlinson (Chief Aerodynamicist)
PredecessorWilliams FW30
SuccessorWilliams FW32
Technical specifications[1]
ChassisCarbon-aramid and honeycomb composite monocoque.
Suspension (front)Carbon fibre double wishbone, with pushrod activated springs. Zero keel geometry.
Suspension (rear)Double wishbone, with pushrod activated springs.
Wheelbase3,100 mm (122.0 in)
EngineToyota RVX-09 2.4 L (146 cu in) 90° V8. Limited to 18,000 rpm; with KERS. Naturally aspirated, longitudinally mid-mounted.
TransmissionWilliams 7-speed electro-hydraulically actuated, semi-automatic, seamless shift.
Weight605 kg (1,334 lb) (including driver)
TyresBridgestone Potenza
Competition history
Notable entrantsAT&T Williams
Notable drivers16. Germany Nico Rosberg
17. Japan Kazuki Nakajima
Debut2009 Australian Grand Prix

Rosberg was criticised for failing to achieve a pole position while topping the times in practices on numerous occasions, notably at the 2009 Brazilian Grand Prix - the Williams cars had excelled during practice sessions in wet conditions, but did not produce the same level of performance in qualifying. While Rosberg often scored points, and elevated the car to a finishing position that it was considered incapable of, Nakajima failed to score a point all season and possibly cost the team a higher position in the championship standings than the seventh place they eventually achieved.

Diffuser controversyEdit

The design of the FW31's diffuser caused controversy when the chassis was launched, but was later cleared by the FIA.

At the first race of the season, an official complaint was launched by other teams against the rear diffusers of the Williams FW31, Toyota TF109 and the Brawn BGP 001 saying that they were illegal,[2] but after analysing the cars the FIA reported that the cars were not illegal.[3] The teams appealed and after much deliberating the car were deemed legal by the FIA.[4]

Season reviewEdit

The Williams FW31 was a slight improvement compared to previous FW28-30 cars as the team tried to get used to the major new rules in 2009. Rosberg proved to be a consistent challenger for points, though he could not clinch a podium finish. It could have been a 2nd consecutive podium finish in Singapore for Rosberg, who was running 3rd before a pit-stop. After the pit-stop his car ran wide, causing a drive through penalty. The safety car was sent out on track, and he could not serve his penalty until the safety car was called in, ending his chances of a podium finish.


Formula One World Championship resultsEdit

(key) (results in bold indicate pole position; results in italics indicate fastest lap)

Year Entrant Engine Tyres Drivers 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 Points WCC
Rosberg 6 8 15 9 8 6 5 5 4 4 5 8 16 11 5 Ret 9
Nakajima Ret 12 Ret Ret 13 15 12 11 12 9 18 13 10 9 15 Ret 13

Driver failed to finish, but was classified as they had completed >90% of the race distance.
Half points awarded as less than 75% of race distance completed.


The Williams FW31 has been featured in the racing simulations F1 2009 and iRacing.


  1. ^ "Car: Tech Spec". Archived from the original on 2013-02-03. Retrieved 2009-02-05.
  2. ^ Official Complaint against Diffusers Archived 2009-03-30 at the Wayback Machine
  3. ^ "Date set for F1 diffuser appeal". 28 March 2009 – via
  4. ^ FIA deem diffusers legal BBC Sport. 2009-04-15. 2009-04-15

External linksEdit