# V2 Vehicle Physics And Handling

§98 is implemented in `V2RacePhysics` as a deterministic arcade-to-sim handling
layer that consumes the §97 vehicle framework data. The core dial is a 0-100
Arcade-Sim spectrum: 0 is assisted arcade handling, 100 is strict sim handling.

## Handling Spectrum

Arcade tuning increases steering response, traction forgiveness,
auto-counter-steer, and assisted braking. Sim tuning lowers forgiveness, raises
yaw damping, preserves realistic grip loss, and makes brake balance matter.

Mode defaults are explicit data. Most Wanted, Blur, and Death Race use dial 20;
GRID, Hot Pursuit, and cops-vs-racers use dial 78; Carbon canyon duels use dial
45; NFSU2 customization racing uses dial 25. Casual modes can persist a player
preference in profile, while ranked resolves to the ruleset-locked dial.

## Driving Assists

The assist library covers ABS, TCS, Stability Control, Steering Assist,
Auto-Brake at Corners, Racing Line Display, Cornering Suggestion, Brake Assist,
Anti-Spin, and Auto-Counter-Steer. Each assist has an independent player toggle
and ranked eligibility cap. Top-tier ranked resolves with disallowed assists
off, preserving casual accessibility without weakening competitive rules.

## Race-Specific Physics

Drafting uses a per-vehicle drag-reduction curve. A trailing vehicle starts
receiving slipstream inside 42 meters and reaches peak reduction near 7.5
meters. Dirty air adds yaw instability under cornering load, while bump-drafting
is legal only in oval-style or explicitly flagged rulesets.

Nitrous data owns capacity, burst duration, boost multiplier, current charge,
and recharge rule. Supported recharge rules are race-victory recharge,
pickup-recharge, and pickup-free with charge bar.

Futuristic speed bands define accelerated speed zones with camera lead distance
so anti-grav and pod-racer modes keep cinematic-aware framing at high speed.

## Weather

Rain reduces grip by 15-25 percent depending on intensity and tire compound.
Snow and ice reduce grip by 30-50 percent and increase slide-prone handling. Sim
rulesets can change weather mid-race; ranked and esports lock weather at event
start. Puddle depth feeds hydroplane risk at speed.

## Determinism And LOD

Online race physics uses fixed-step 60 Hz simulation, quantized floating point,
and deterministic input streams. For racing events with up to eight players, the
same input stream and RNG seed must produce the same frame hash across clients.

Physics LOD switches vehicles beyond 200 meters behind the player, or offscreen
vehicles, to reduced-fidelity simulation. Visible reduced vehicles use pose
interpolation for accuracy rather than snapping.

## Verification

`RacePhysicsHandling_V2_Contract.json`, `handling-spectrum.json`, the
`RacePhysics.Module` automation spec, and `check-v2-race-physics-handling.py`
are the signoff surface for §98.