Rear wing reduction and straight-line acceleration
Drag Reduction System (DRS) opens the rear wing flap on straights, reducing aerodynamic drag at the cost of rear downforce. On a long straight like Monza's main straits, a car with DRS activated gains 8-15 km/h of top speed compared to the car ahead. This advantage persists only in designated DRS zones; once braking begins, the flap closes and downforce returns.
The speed advantage is largest on circuits with long straights and small on circuits with frequent corners disrupting acceleration. A pursuing car using DRS can deploy this advantage once per lap if trailing within one second of a car ahead. Without DRS, overtaking on modern high-downforce cars becomes nearly impossible due to aerodynamic drag from running close to another car.
Strategic timing and fuel-load interaction
DRS effectiveness decreases as fuel load increases; a car carrying 50 kg of fuel accelerates slower than one with 10 kg. Late-race DRS is less effective than early-race DRS because fuel consumption is gradual. A team chasing another car on the final lap has maximum DRS benefit (minimum fuel, maximum clarity on pursuer's setup), while a pursuer on lap five faces headwinds from fuel weight.
Teams exploit this by timing pit stops to position faster cars on lighter fuel when a championship rival is heavy. A defending driver might fuel conservatively, knowing the pursuer's weight will reduce DRS advantage, then rely on tire degradation management to survive the sprint to the finish.