I've got one of the realtime ammeter gauges in my 240z, Came that way from the factory till 75 or so when they switched over to fuel injection then it became a boring old voltmeter. It's nice other than the fact it's essentially channeling all the current being used in the car though that gauge at any given time. Definitely is realtime though, if you leave your lights on for a while and then drive it it'll show that it's charging when it is.