Reverse also exhibits the same problem when trying to apply brakes (in vid am pressing S and holding spacebar)

Additional related bug found after further testing:

vehicles lose almost all braking power if engine is turned off, either by purposefully turning it off or by running out of fuel.

1. spawn veh at top of hill, give it 1% fuel
2. drive it down the hill
3. When fuel empties (or when you turn off the engine manually) note that braking does not work, regardless of if you shift to N or drive gears

Well cars normally use vacuum from the engine running, to power the brakes (brake servo/booster)
So that is probably intended

In T189237#2798853, @lwing wrote:

Additional related bug found after further testing:

vehicles lose almost all braking power if engine is turned off, either by purposefully turning it off or by running out of fuel.

1. spawn veh at top of hill, give it 1% fuel
2. drive it down the hill
3. When fuel empties (or when you turn off the engine manually) note that braking does not work, regardless of if you shift to N or drive gears

In T189237#2799229, @byNautiic wrote:

Well cars normally use vacuum from the engine running, to power the brakes (brake servo/booster)
So that is probably intended

Yes sir vehicles use vac assisted brakes aka power brakes that help assist the driver by making it require less force to push the brake pedal. Prior to power brakes it would require you to push hard on the pedal to apply full brake force aka 'manual braking'

In an engine out situation you would no longer have power brakes but can still manually brake and get full braking force just like we had to do in the old days.

In T189237#2799229, @byNautiic wrote:

Well cars normally use vacuum from the engine running, to power the brakes (brake servo/booster)
So that is probably intended

In T189237#2798853, @lwing wrote:

Additional related bug found after further testing:

vehicles lose almost all braking power if engine is turned off, either by purposefully turning it off or by running out of fuel.

1. spawn veh at top of hill, give it 1% fuel
2. drive it down the hill
3. When fuel empties (or when you turn off the engine manually) note that braking does not work, regardless of if you shift to N or drive gears

I'm more inclined to think it's a bug, as there's nothing wrong with the function of the brake itself you just need more power to use it