Not really applicable without further info. You could have bought a non plug in Prius and saved a ton if your previous car didn't do nearly as well mpg. You aren't going to save enough with current prices over plugging in versus not plugging in. You do it because it's a bit cleaner.
I don't buy new cars, I only buy used. You just take too much of a hit on value on a new car for it to ever be worth it. (Ok, sure, if I were filthy rich I'd buy a new Tesla, but only because I'd want the option of full self-driving when they finish the software and of course the Ludicrous mode. But I'm not filthy rich, so that's not happening.)
A used 2013 Prius would have been more expensive than my 2013 C-Max, doesn't handle nearly as well, doesn't accelerate as well, isn't as comfortable, and I can't fuel it up in my driveway. Literally the only thing on the plus side for the Prius was the digital speedometer, I hate the analog speedo in the C-Max. If the cargo space hadn't been so much better in the C-Max, I'd have probably gotten a Volt just because of that. The Prius wasn't even in the running because it's just too slow. (10+ second 0-60 is not acceptable.)
The convenience of that driveway fueling would have been worth paying more for the car, it's a bonus that the car was actually less expensive than anything comparable. Before last year, I was at the gas station a few times a week. For the last year, it's been about once a month.
Cleaner is great. But it's cheaper too.