I've been content with my 2013 Prius C since I purchased it new in 2014 - now about about 102k miles - I've noticed that the mpg has dropped over the last several months. Now I typically only get 40mpg, whereas I used to get high 40's and higher on occasion. I usually have a bit of a drop over winter, but cold temps are over and I swapped back to my "summer" tires a month ago - still the mpg hasn't bounced back up. Is this to be expected with the older vehicle? I've driven prior (non-hybrid) vehicles over 100k miles and not experienced a change like this.
do you measure mpg's by the tankful? what were they before, and what are they now? generally speaking, you shouldn't see a drop unless something has changed. things to check: wheels spinning freely, engine air filter, throttle body, 12 volt health, tyre pressures, changes to driving routes and habits. I suppose the hybrid battery could be a little weaker
Mileage will drop when the hybrid battery ages out. Yours is old enough that this is a real possibility. First things first- check the battery cooling fan under the left rear seat. There are youtube videos showing how to clean the vent and fan using a only screwdriver and a vacuum cleaner.
