The experimental changes are now on the stable branch.
Immersion pass
Did some work on the visual and sound effects in an effort to improve gameplay simply by removing immersion-breaking effects. I'd say it was a success and I'm enjoying battles more.

Basic transmission editing
Introduces a simplified transmission editing screen. This condenses most of transmission design into 5 options, which should be a little more accessible.

Also note the new centre of mass, indicated by the blue diamond. This gizmo can be hidden in the overlay settings.
Dynamic centre of mass
Centre of mass (COM) is now calculated inside and outside of the editor. The COM is now generally a lot higher (was previously fixed 0.1m above the bottom of the hull), resulting in vehicles rocking more. A heavy gun barrel on a light vehicle might cause the vehicle to lean when the turret is rotated to the side. Heavy frontal armour and powertrain components need to be balanced or compensated for via suspension positioning. So another nice bit of depth to tank design.
Changes
- Vehicle centre of mass is now calculated.
- Added a 'basic' transmission editing mode.
- Reworked visual effects for cannon fires, shell impacts, turret popoffs, flameouts, vehicle fires and track throwoff.
- Reworked audio effects for cannon fires and shell impacts.
- Added a sound effect when blown-off turrets hit the ground.
- New part from Dario: triple pad track belt segment.
- Bot gunners now have a reaction time, between 0.1 and 0.5s. The gun will need to be held on the target for this period. Stops them firing accurately on the move.
- Added a 'balanced' bot mode. They'll fire a few shots before advancing in a cycle. Applied to custom battles bots and ally bots in Railway.
- Hatch pressure limits are now slightly randomized. Flameouts will no longer always blow all hatches, instead they'll blow the weakest first, which might lower pressure enough to prevent other hatches blowing.
- Bots without a target will now search for enemies they've lost sight of.
- Projectile lifetime increased from 5 to 10s.
- Recoil energy absorption reduced from 99.9% absorbed to 99.75% absorbed. So recoil is 2.5x higher.
- Reduced how much camera shake falls off by zooming out.
- Reduced lingering smoke at stand-still.
- Improved look of smoke stacks and reduced flickering.
- Smokestacks now cast shadows.
- Track throwoff is now stronger on the part of the track that has more recently been on the ground.
- Transmissions will now only lose torque output if their health drops below 10%. This fixes the driver shifting to final gear upon receiving any transmission damage.
- Transmissions now get stuck in the current gear if their health drops below 60%.
- Fixed instability caused by the 'Point Normal' freeform thicken mode.
Optimizations
- Optimized distant visual effects.
- Optimized GPU usage of all smoke visual effects.
- Smoke visual effects are now rendered at a lower resolution, significantly reducing GPU cost (especially on weaker GPUs).
- Collisions can now be disabled for addon structures (collisions disabled by default). Allows for some big CPU savings for vehicles using a lot of them.
- The number of engine fire effects per-vehicle is now limited to 2.

Also some new track belts. Always nice.
- Hamish