there should really be a way to put a car in neutral so you can throttle up without moving so you can get more power while stationary
So just FYI, what you’re describing is both marginal and very wasteful.
As stated you’re going to double or more your gas consumption (probably way more) and increase power output by like 30%.
If you want more power output the best option is to install more/bigger alternators or use a dedicated generator.
You can have multiple alternators on one engine?
And yeah obviously a dedicated generator would be more efficient, but it’s also not always an option, irl putting the car in neutral and maxing the throttle wasted gas but it’ll power the car, letting you charge your phone or run the heat a bit longer if fuel isn’t an issue, it makes more sense for it to be in the game then it does not to