2009 · TECHNICAL
2009 Technical Regulations
2009 is one of the most consequential reset years of the V8 era. Major changes: (1) KERS (Kinetic Energy Recovery System) debuted as an optional device storing braking energy and releasing up to 60 kW for 6.67 s/lap; (2) slick dry tyres returned, replacing the 4+4 grooves that had been standard since 1998; (3) aerodynamic regulations were rewritten to reduce front-wing endplates, raise the rear wing, allow a wider front wing with driver-adjustable flap, and cut diffuser power — though the latter was immediately undermined by the 'double diffuser' interpretation found by Brawn, Williams and Toyota. Brawn GP (using Mercedes engines and the banned-mid-year double diffuser) won both titles in the team's only season.
KERS debut
KERS stored braking energy in a battery or flywheel and released it through an electric motor bolted to the engine. The FIA allowed up to 60 kW of boost for 6.67 seconds per lap (400 kJ total). Adoption was mixed in 2009 — some teams ran KERS, others didn't; the device was optional. Ferrari, McLaren, BMW, Renault ran KERS; Brawn, Williams, Toyota, Red Bull did not. KERS was absent from 2010 before returning as a widely-adopted 'voluntary' system in 2011.
Key changes
- KERS introduced (optional): 60 kW / 6.67 s / 400 kJ per lap.
- Slicks return (end of 1998-2008 grooved era).
- Aero reset: narrower rear wing, wider front wing, driver-adjustable front flap.
Double-diffuser controversy
The 2009 aero regulations contained an exploitable ambiguity that Brawn, Williams and Toyota interpreted to produce a second diffuser volume behind the primary one, roughly doubling diffuser-derived downforce. The FIA initially declared the device legal and it was not banned until the 2011 regulations. The double-diffuser effect was widely credited with Brawn's 2009 title run.
Last updated: 2026-04-24
This summary is editorial material prepared by F1pedia for general F1 audiences. It is not a legal reference. For binding rule text, consult the official FIA document.