Код:

<VehicleConstraint>
<ReverseGear
	Torque="20000"
	AngVelMin="-2.0"
	AngVelOpt="1.0"
	AngVelMax="8.0"
	MaxDeltaAngVel="0.1"
/>
<HighGear
	Torque="20000"
	AngVelMin="1.0"
	AngVelOpt="10.0"
	AngVelMax="12.0"
	MaxDeltaAngVel="0.15"
/>
<Gear
	Torque="20000"
	AngVelMin="-2.0"
	AngVelOpt="1.0"
	AngVelMax="10.0"
	AutoNextLinVel="2.5"
	MaxDeltaAngVel="0.12"
/>
<Gear
	Torque="16000"
	AngVelMin="-1.5"
	AngVelOpt="2.8"
	AngVelMax="16.0"
	AutoNextLinVel="3.5"
	MaxDeltaAngVel="0.1"
/>
<Gear
	Torque="12000"
	AngVelMin="0.4"
	AngVelOpt="4.5"
	AngVelMax="24.0"
	AutoNextLinVel="5.0"
	MaxDeltaAngVel="0.05"
/>
<Gear
	Torque="8000"
	AngVelMin="0.5"
	AngVelOpt="8.0"
	AngVelMax="32.0"
	AutoNextLinVel="6.0"
	MaxDeltaAngVel="0.05"
/>
<Gear
	Torque="6000"
	AngVelMin="8.5"
	AngVelOpt="16.0"
	AngVelMax="48.0"
	MaxDeltaAngVel="0.05"
/>
	</VehicleConstraint>

Gear\ReverseGear\HighGear - передача передняя\задняя\1+
Torque - максимальный крутящий момент (суммарный для всех колёс) прилагаемый когда движок молотит на полную. Зависит от массы шасси (???)
AngVelMin\AngVelOpt\AngVelMax - зависимость между величиной прилагаемого момента и угловыми скоростями колёс, т.е. когда угловая скорость колеса будет равна значению AngVelOpt на колесо будет даваться максимальный крут.момент, при AngVelMax ничего крутиться не будет а при AngVelMin будут давать либо усреднённый момент либо вообще ничего.
LinVelMax - см. AngVelMax, его линейный эквивалент
AutoNextLinVel - линейная скорость, при которой включается следующая передача в режиме "Авто"
MaxDeltaAngVel - максимально возможное ускорение угловой скорости колеса

Vehicles (*)
    Spin Tires vehicle descriptions.

    Some brief documentation of the vehicle format -

    <Gear
    Torque="120000"
    AngVelMin="-2.0" AngVelOpt="2.0" AngVelMax="6.0"
    LinVelMax="1.5"
    MaxDeltaAngVel="4.0"
    />
    Torque is maximum torque (summ for all wheels) applied when engine torque factor is = 1 (that is, acceleration fully pulled), its physics quantity, angular equivalent of force... in short, it depends on chassis mass.
    AngVelMin, AngVelOpt, AngVelMax define the engine torque. It depends on the angular velocity of the wheel. So engine applies maximum torque when wheel is spinning with angular velocity = 2.0, and zero torque for -2.0 or 6.0 (wheels spinning backwards wont be accelerated, and wheels spinning too fast wont be neither)
    LinVelMax limits maximum vehicle linear velocity for this gear, by again modulating engine torque
    MaxDeltaAngVel prevents wheels from accelerating too fast. This hack is required beccause its VERY difficult to predict what torque should be applied to wheel on current game frame. In real world, I guess its due to materials friction, but in a game, if you apply high torque to a wheel hanging in air it will go totally nuts, and if you apply small torque to a wheel in mud, it wont move <Engine> and <Transmission> sections are not used right now. these are fast truck physics. Actually you can read all about it in Havok documentation. So current physics model I call 'constraint vehicle', so attributes with 'Constrained' prefix affect it

<ReverseGear
Torque="60000"
AngVelMin="-2.0" – average wheel angular velocity at which torque is applied to wheels
AngVelOpt="1.2" – angular velocity at which maximum torque is applied
AngVelMax="8.0" – angular velocity at which torque is no longer applied
LinVelMax="1.8" – linear velocity at which torque is no longer applied
MaxDeltaAngVel="0.1"- maximum increase to angular velocity for given vehicle
/>