Drive a hill-climb taxi 1200 meters from the depot to the airport. A wobbly bucket of green slop is bolted to your roof.
Hills tilt the car. Bumps slosh the liquid. Hard braking sends it flying forward, hard gassing sends it sloshing back. Tap the slop directly to push the wave down before it spills.
Desktop: ← BRAKE, → GAS, click the bucket to stabilize. Mobile: pedals + tap the bucket.