Every achievement now comes with a wheel.

Full Changelog

• added a bunch of new wheels
• added reverb and a lowpass filter if the car is far away from the camera, for slight added realism
• tweaked visual wheelspin when drifting at low speeds
• inputs for car air control are now rounded to improve control when using the right stick for multiple axes
• increased angular drag for car in the air (it stops spinning faster if there are no rotation inputs)
• increased the time it takes for the engine to return to idle RPM when the clutch is in. perfect shift timing is unchanged
• decreased volume of idle engine noise
• decreased grip and disabled TCS when the car is experiencing low-downforce conditions
• removed loud wind noise that would play sometimes at the level start
• award nitro for clean landings, based on airtime

Low-Downforce Conditions

When the car is driving up a steep wall, or cresting a little hill, grip decreases. You’ll notice this in bits of Turbine Climb and other tracks that might require you to take a more specific racing line to avoid convex surfaces.

This generally mimics real life. IRL, the less force you put on tires, the less they grip.

In my simulation, a graph of grip would look like a flat surface, then a cliff and then a downwards slope - you’re at full-grip until you drop below that 0.5 spring compression threshold, and then you lose grip rapidly. I designed it this way to be more predictable until you hit that threshold, much like the drift mechanics. I may change it later on.

I calculate this by determining the resting suspension compression distance, i.e. the compression distance of the springs when the car is sitting at rest. The formula for that, since there are four springs, is:

(car_mass * gravity) / (4 * spring_strength)

Then, while the car is moving, I look at the moment-to-moment average suspension compression ratio compared to the resting compression ratio. So if the resting suspension compression distance is 0.1, and the current distance is 0.07, the current compression ratio is 0.7. The number will decrease as the car moves away from the ground and increase as the car moves toward the ground.

At a value of 0.5, the car’s suspension springs are only compressed half as much as when the car is sitting still at rest. Below that threshold, you lose grip and TCS/LCS turn off. I’m probably going to have to make a little car-skid light or something to make that more obvious to the player.

I should also add that I’ve been calculating downforce on the car for a while. It hasn’t really meant anything besides pushing the car’s physics object downwards at high speeds, but I was able to see with the telemetry that it does in fact affect the spring compression ratio as the car goes faster on flat ground.