Beta ETK800 Hybrid 8.1.0

The electric sound is proportionate to how much power is going to the motor, so if you're not accelerating a lot, you won't hear it much. The engine will kick in any time you accelerate too hard or go too fast unless it's in "forced EV" mode toggled by pressing "E"

Have you tried restarting the game since subscribing to the mod? Also, if you have any other mods installed that would change the ETK800 powertrain, there is a chance they might conflict with the device options for the ETK

I think I know the problem you're referring to...there's an actual bug in the game itself when a vehicle with custom powertrain devices is loaded before any other vehicles. If you load another vehicle (not another configuration, another vehicle altogether) before loading the ETK800 or the Citybus, you should then be able to switch to a normal configuration just fine.

You can actually swap the built-in ETK I4 engine in and it'll work fine ;) I didn't include a configuration for that, but you could save your own. I haven't found a way to do custom tachometers yet but that'd be a neat idea

This one will shut the engine off even without the brake pedal pressed, as long as you're under a certain speed. The coolant has to be warmed up enough. I made a forum post last month about an experimental "auto-stop" like you're describing for a non-hybrid vehicle but I haven't released it as a mod.