You're following a car at speed, with the gap you choose. When it brakes, brake. Five rounds: find out whether your gap survives an emergency stop, or how hard it fails.
You're following a car at speed. When it emergency brakes, hit the brake as fast as you can. Watch the gap close in real time and find out if you would have crashed.
Standardised Conditions
To make results comparable, this simulation assumes identical conditions for both vehicles:
- Both vehicles: Standard mid-size sedan (e.g., Toyota Corolla class) — same make, model, weight, and brake system
- Both tyre sets: Premium all-season tyres (EU wet grip grade A/B) at 80% tread depth (~6mm), correctly inflated
- Road surface: Sealed asphalt in good condition — no potholes, gravel, or oil
- Gradient: Flat road — no uphill or downhill slope
- Driver position: Right foot covering the brake pedal (not resting on the accelerator)
Deceleration Rates
- Emergency brake (dry): Lead car decelerates at 9.5 m/s² (ABS-assisted maximum on dry sealed road). You decelerate at 7.0 m/s² — lower because a reacting driver applies the brake progressively, not as a single optimal input
- Emergency brake (wet): Lead car at 6.5 m/s², you at 5.0 m/s² — grip reduced ~30% on a wet surface with good tyres
- Gradual stop (dry): Lead car at 4.0 m/s² (controlled deceleration). You brake harder at 7.0 m/s² once you react
- Gradual stop (wet): Lead car at 2.8 m/s², you at 5.0 m/s²
What This Doesn't Model
- Tyre condition variation: Worn tyres (1.5mm tread) can need 30–50% more braking distance than new tyres — especially in the wet. This simulation uses good tyres for both cars
- ABS quality differences: Budget vs premium ABS systems have measurably different stopping performance
- Vehicle weight: A loaded ute or SUV stops significantly slower than an empty sedan
- Road temperature: Hot bitumen in NZ summer reduces grip; cold mornings may have dew or frost
- Driver foot position: Real-world reaction includes moving your foot from accelerator to brake — we measure from visual stimulus only
- Brake fade: On long downhill stretches, brakes lose effectiveness — not modelled here
Why the Lead Car Stops Faster
In emergency mode, the lead car decelerates at 9.5 m/s² while you only get 7.0 m/s². This is deliberate and realistic — the lead driver is initiating the stop (foot already moving to brake, optimal pedal application), while you are reacting (processing the visual, making a decision, then progressively applying the brake). Even after you start braking, the gap continues to close because they are decelerating harder. This is why following distance matters so much.
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