I have a 2013 liftback with 2500 miles on it. After typical drives of 15-20 miles when I stop and shutdown the car I see the mpg readout during that trip to be in the 50-54 mpg range. Today I saw my last two trips over the same path record 62 and 70 mpg. This is pretty flat driving and not down hill. I'd like to believe that I am getting that type mileage; that I've learned to be a great hypermiler, but I suspect something is wrong with the sensors or something. Is this a known problem? I imagine I will get a reality check next time I do a fillup and I do a calculation by hand but I am curious why this would happen.
Better weather? Moderate speeds with favorable traffic and lights? Hot restarts producing less engine warmup penalty? With favorable conditions, your observed numbers are very believable. For single trip segments, I've reached into the 70s numerous times, just not in the winter weather my region has now. Remember that even very small elevations changes, smaller than you may notice, can greatly help one-way trip mpg. But the reverse trip will extract a payback.
Dash mpg and hand calculated mpg is always a little off. I'm using Fuelly to calculate my mileage. Total gallons going into the tank and odometer reading. The difference between Prius vs Fuelly is about 3-5mpg in my experience. Other gauges are also a little off like the speedometer, 2 mph difference Dash vs GPS at 60mph. I think my car just likes to give me a pat in the back now and then and keep me from speeding Depending on your driving style and conditions, the mileage you mentioned is not uncommon. Check out threads like the 700-800 miles club. There are quite a few hyper-milers that can go well over 600 miles every tank.
