Interpolation problems? (Jumpy players)

datablock WheeledVehicleData(DefaultCar)
{
   category = "Vehicles";
   shapeFile = "~/data/shapes/buggy/buggy.dts";
   emap = true;

   maxDamage = 1.0;
   destroyedLevel = 0.5;

   maxSteeringAngle = 0.785;  // Maximum steering angle, should match animation
   tireEmitter = TireEmitter; // All the tires use the same dust emitter

   // 3rd person camera settings
   cameraRoll = true;         // Roll the camera with the vehicle
   cameraMaxDist = 10;         // Far distance from vehicle
   cameraOffset = 1.5;        // Vertical offset from camera mount point
   cameraLag = 0.1;           // Velocity lag of camera
   cameraDecay = 0.75;        // Decay per sec. rate of velocity lag

   // Rigid Body
   mass = 200;
   massCenter = "0 -0.5 0";    // Center of mass for rigid body
   massBox = "0 0 0";         // Size of box used for moment of inertia,
                              // if zero it defaults to object bounding box
   drag = 3;                // Drag coefficient
   bodyFriction = 0.3;
   bodyRestitution = 0.3;
   minImpactSpeed = 0.1;        // Impacts over this invoke the script callback
   softImpactSpeed = 5;       // Play SoftImpact Sound
   hardImpactSpeed = 15;      // Play HardImpact Sound
   integration = 8;           // Physics integration: TickSec/Rate
   collisionTol = 0.1;        // Collision distance tolerance
   contactTol = 0.1;          // Contact velocity tolerance

   // Engine
   engineTorque = 15000;       // Engine power
   engineBrake = 10000;         // Braking when throttle is 0
   brakeTorque = 13000;        // When brakes are applied
   maxWheelSpeed = 800;        // Engine scale by current speed / max speed


   // Energy
   maxEnergy = 100;
   jetForce = 3000;
   minJetEnergy = 30;
   jetEnergyDrain = 2;

   // Sounds
//   jetSound = ScoutThrustSound;
//   engineSound = BuggyEngineSound;
//   squealSound = ScoutSquealSound;
//   softImpactSound = SoftImpactSound;
//   hardImpactSound = HardImpactSound;
//   wheelImpactSound = WheelImpactSound;

//   explosion = VehicleExplosion;
};