I am trying to make a vehicle behave realistically on second life.

I got a speedometer attached to my hud that measures the speed I go in miles per hour. Now that I have this, I want to modify the script I have here so that the vehicle will accelerates from 0 - 60 miles per hour in 7.5 seconds, with a max speed of 140 miles per hour.

The problem is I don't know how to modify this script in this way, but I suspect it has to do with tweaking the following. (but I could be wrong)

VEHICLE_LINEAR_FRICTION_TIMESCALE
VEHICLE_LINEAR_MOTOR_TIMESCALE
VEHICLE_LINEAR_MOTOR_DIRECTION

Now I think I got the VEHICLE_LINEAR_MOTOR_DIRECTION figured out. I think this controls the max speed of the vehicle and I figured that a formula like (MPH you want to go x 2.23694) will output the correct number in Meters Per Second. My code I will show will reflect this, but what about the VEHICLE_LINEAR_FRICTION_TIMESCALE and VEHICLE_LINEAR_MOTOR_TIMESCALE. Can you come up with any formulas or strategies to make these behave within the paramaters I specified above? Here is the vehicle code.

    default
    {
    	state_entry ()
    	{
    		llPassCollisions(TRUE);
    		llPassTouches(FALSE);
    		llSetSitText("Ride");
    		llSitTarget(<0.6,0,0.25>, ZERO_ROTATION);
    		llSetCameraEyeOffset(<-7.0, 0.0, 1.0>);
    		llSetCameraAtOffset(<3.0, 0.0, 2.0>);
    		llSetVehicleType(VEHICLE_TYPE_CAR);
    		llSetVehicleFlags(VEHICLE_FLAG_CAMERA_DECOUPLED
    						| VEHICLE_FLAG_LIMIT_MOTOR_UP
    						| VEHICLE_FLAG_MOUSELOOK_BANK
    						);
    			  
    		//Controls how easy it glides along the ground.
    		llSetVehicleVectorParam( VEHICLE_LINEAR_FRICTION_TIMESCALE, <1000, 0.0, 1000> );
    		//Controls how easy the vehicle rotates.
    		llSetVehicleVectorParam( VEHICLE_ANGULAR_FRICTION_TIMESCALE, <1000, 1000, 0> );
    					  
    		//Determines how long it takes for the motor to push the vehicle to full speed. 
    		//Its minimum value is approximately 0.06 seconds.
    		llSetVehicleFloatParam( VEHICLE_LINEAR_MOTOR_TIMESCALE, 2 );
    		//Controls the deceleration to zero velocity from the time you let go of the pedal.
    		llSetVehicleFloatParam( VEHICLE_LINEAR_MOTOR_DECAY_TIMESCALE, 0.0);
    		
    		llSetVehicleFloatParam( VEHICLE_LINEAR_DEFLECTION_EFFICIENCY, 0.0 );
    		llSetVehicleFloatParam( VEHICLE_LINEAR_DEFLECTION_TIMESCALE, 0.0 );
    		
    		//Controls the max turning rate.
    		llSetVehicleVectorParam( VEHICLE_ANGULAR_MOTOR_DIRECTION, <1000, 1000, 0> );
    		//Controls the time it takes for the turning rate to accelerate to max velocity.
    		llSetVehicleFloatParam( VEHICLE_ANGULAR_MOTOR_TIMESCALE, 0.0 );
    		//Controls the time it takes for the turning rate to decelerate to zero velocity.
    		llSetVehicleFloatParam( VEHICLE_ANGULAR_MOTOR_DECAY_TIMESCALE, 0.0 );
    		llSetVehicleFloatParam( VEHICLE_ANGULAR_DEFLECTION_EFFICIENCY, 0.0 );
    		llSetVehicleFloatParam( VEHICLE_ANGULAR_DEFLECTION_TIMESCALE, 0.0 );
    		
    		//Controls how strong the force for the bike to remain vertical
    		llSetVehicleFloatParam( VEHICLE_VERTICAL_ATTRACTION_EFFICIENCY, 0.50 );
    		//Controls the time it takes for the bike to lean.
    		llSetVehicleFloatParam( VEHICLE_VERTICAL_ATTRACTION_TIMESCALE, 0.50);
    		
    		llSetVehicleFloatParam( VEHICLE_BANKING_EFFICIENCY, 1.0 );
    		llSetVehicleFloatParam( VEHICLE_BANKING_MIX, 1.0 );
    		llSetVehicleFloatParam( VEHICLE_BANKING_TIMESCALE, 0.0 );
    	}
    
    	changed(integer change)
    	{
    		if (change & CHANGED_LINK)
    		{
    			key agent = llAvatarOnSitTarget();
    			if (agent)
    			{
    				if (agent != llGetOwner())
    				{
    					llSay(0, "You are not the owner of this vehicle. Please step away.");
    					llUnSit(agent);
    					llPushObject(agent,<0,0,10>, ZERO_VECTOR, FALSE);
    				}
    				else
    				{
    					llSetStatus(STATUS_PHYSICS, TRUE);
    					llRequestPermissions(agent, PERMISSION_TRIGGER_ANIMATION | PERMISSION_TAKE_CONTROLS);
    					llOwnerSay("'W' Accelerates, 'S' Decelerates/Reverse. Steer by looking in the direction you want to go.");
    				}
    			}
    
    			//... Permissions may already be revoked on standing ...
    			else
    			{
    				integer p = llGetPermissions();
    				llSetStatus(STATUS_PHYSICS, FALSE);
    				if(p & PERMISSION_TAKE_CONTROLS)
    				{
    					llReleaseControls();
    				}
    				if(p & PERMISSION_TRIGGER_ANIMATION)
    				{
    					llStopAnimation("motorcycle_sit");
    				}
    			}
    		}
    	}
    
    	//... may be called multiple times ...
    	run_time_permissions(integer perm)
    	{
    		if (perm & PERMISSION_TRIGGER_ANIMATION)
    		{
    			llStopAnimation("sit");
    			llStartAnimation("motorcycle_sit");
    		}
    		if(perm & PERMISSION_TAKE_CONTROLS)
    			llTakeControls(CONTROL_FWD | CONTROL_BACK, TRUE, FALSE);
    	}
    
    	control(key id, integer level, integer edge)
    	{
    		if(level & CONTROL_FWD)
    		{
    			//This sets the max velocity the vehicle will achive by meters/second (miles per hour you want to go x 2.23694 = meters per second value)
    			llSetVehicleVectorParam(VEHICLE_LINEAR_MOTOR_DIRECTION,<140*2.23694,0,0>);
    		}
    		if(level & CONTROL_BACK)
    		{
    			//This sets the max velocity the vehicle will achive by meters/second (miles per hour you want to go x 2.23694 = meters per second value)
    			llSetVehicleVectorParam(VEHICLE_LINEAR_MOTOR_DIRECTION,<-140*2.23694,0,0>);
    		}
    	}
    }
    

Also if you see any errors in the comments, please point them out so I can have the right changes?

The max speed i bleive in SL is 32 m/s, or about 71mph.