Help - Vehicle perks

[kiliki]

I've just started modding the game and so far it's been great fun but I've hit a roadblock. I'm trying to add a perk that improves the player's driving stats (max speed, hop strength, etc).

The new skill comes up in the skills menu, but when I level it up it has no effect. If I change it to stamina gain or reload speed it works fine, but it doesn't seem to affect driving skills at all.

<!-- These work -->
<passive_effect name="StaminaChangeOT" operation="perc_add" value="0.5,1.5" level="1,5" tags="running"/>
<passive_effect name="ReloadSpeedMultiplier" operation="perc_add" value="0.5,1.5" level="1,5"/>

<!-- These don't -->
<passive_effect name="VehicleSpeedMax" operation="perc_add" value="0.5,1.5" level="1,5"/>
<passive_effect name="VehicleBoostedSpeedMax" operation="perc_add" value="0.5,1.5" level="1,5"/>
<passive_effect name="VehicleHopStrength" operation="perc_add" value="0.5,1.5" level="1,5"/>

I'm not sure if I'm missing a few steps or if the player's stats simply can't affect vehicles - can anyone help me out?

Thanks