I will freely admit that my motivation to buy a Prius back in 2010 was equal parts gadget lust and smug tree-hugger desire. I was surprised to find that I could pretty easily push it to 56 mpg on my work commute, especially on the shorter drive with fewer hills. It probably didn't hurt that most of the road I traveled on was 35 mph.
When that car was totalled in The Great Christmas Eve Crash of 2011, we replaced it with the Prius V, the wagon variant that is "only" rated for 44 mpg city and 40 mpg highway. It has the same drivetrain as the regular Prius, but it's a little heavier, larger and has a "big ass" so there's a lot more drag.
The problem with a hybrid in winter is that it often doesn't make enough heat to keep you warm. During those times when the gas engine isn't running, the heat that bleeds off the coolant system seems to run off pretty fast. That means it has to fire up the engine not to propel the car, but to keep you toasty. It's either that, or the computer just prefers to keep the engine at a certain temperature. Regardless, the gas engine runs more when it's below freezing, and your fuel economy suffers.
Fortunately, it's getting warmer, and I have a commute with zero highway. Instead I have a series of country roads with speed limits generally around 45, and few stops. A sleepy town with one traffic light sits in the middle. This is pretty much the perfect environment to see how far I can push the car.
I ended the last tank of gas on 48 mpg, which is really fantastic. The first day after the fill-up, I did 52 mpg one-way (job site is lower elevation than home). It might have ended higher if I didn't go downtown over the weekend. I've theorized that I could get the car to do close to what a regular Prius does at lower speeds, since it's the same drive train and there's less aerodynamic drag at lower speeds. Yes, it has become kind of a sport for me.
There's a lot of discipline to follow. The first thing is to not be in a hurry. The second is to not use the "PWR" mode of the car. People don't realize that a Prius is actually a crazy peppy car (duh, it combines electric and gas motors!), but the software in standard mode is designed to keep you in check. Then you do what you can to coax the car into EV mode, which usually involves getting up to 40 or so in a 35, then dropping off the accelerator and back up to push the meter on the dash just below the gas engine threshold. Of course you coast anywhere you can. You don't floor it when you start from a stop. If no one is behind you, you coast even longer than usual.
The funny thing is that it's not about the cost of gas or the environment. It's more like the satisfaction you get from mastering a video game. You're going for the high score.