[Bearleener]

I measured the injector pulse width with a multimeter's duty cycle setting and yes, the injector shut off completely. Unfortunately on my car that only happens above about 1700-1800 rpm, i.e. it only helps on the highway. Most more modern cars do this down to a considerably lower speed. It could be that some cars add a tiny bit of fuel, possibly because at lower engine speeds it might otherwise jerk a bit when you add gas again. I'm pretty sure that a mid '80's car would already have fuel cutoff. The Golf II did (1983-1992).

I suspect that in city driving it doesn't make sense to downshift when approaching a stoplight just to activate fuel cutoff. In almost all cases it's better to let 'er roll in neutral, i.e. anticipate the light when possible.