Greatly reducing (let alone eliminating) my car usage wasn't a motivating factor when I decided to get an ebike earlier this year.
But, I did start out at the purchase decision, anticipating that I would commute to work whenever possible/practical (ie, when the morning temp is above freezing, and it is not raining heavier than a sprinkle at that time.)
In that regard, it has replaced 49 office commutes since starting in April, eliminating about 655 car miles so far. All the other ~1,600 biked miles I've accumulated this year are either for fun or for exercise riding -- they're not miles I would have otherwise covered in a car.
I'm still working on getting "organized" enough (ie, mostly advance planning and forethought) to start making more frequent, yet smaller, bike-limited grocery runs on the ride home from work (vs. making a bigger shopping load via car every 8-10 days.)