Drastic drop in MPG

Have you read This Thead Yet? -yes

- What fuel economy are you getting and how are you determining fuel economy? (trip computer or manual calculations) 30+/- a few

- What fuel economy are you expecting and why? Normally in the mid 40'

- What are the approximate outside air temps? 10-40 depending

- How long are your trips? Short 1-2 miles

How old is your 12v battery? What is the voltage reading of your 12v battery after sitting over night? (Method Here) 7 years original

Have you had your alignment checked? Any pulling or abnormal tire wear? OK

- How much of it is city vs. highway? Roughly what's the average speed in overall and and of each segment? Is there a lot of stop and go driving? 40 miles average speed

- What's the terrain like of your drives? (e.g. flat, gentle hills, steep hills, etc.) Steep hills

- What are your tire pressures? 35

- Is your oil overfilled? (i.e. above the full mark on the dipstick) no

- Make, model, year, engine and transmission of previous car? (e.g. 08 Honda Civic Si 2.0L 4 cylinder, manual transmission) What did you actually get on the same trips/commute? (Please give us actual numbers, not EPA ratings.) 2004 Lexus RX330 - 17 mpg Still own

- What region/state are you in? (if you haven't set your location) West Virginia

- How are you trying to drive (e.g. trying to stay in electric only?) and how hard are you braking? gentle driver on gas and brakes

- What modes are you using, if any? "normal", EV, power, eco? ECO

- Are you "warming up" the ICE (internal combustion engine) by letting it idle after powering on? No

- Are you driving using D or B mode? D

- HVAC settings? Are you using the heater, AC, auto mode, etc.? If using auto, what temp is it set to? as required

- Are you using the factory tires and wheels? If not, please indicate tire make, model and size (e.g. Goodyear Assurance Fuel Max 185/65R15).

- If reporting a mileage drop, did anything significant change on your car (e.g. accident, hit a curb or big pothole throwing off alignment, oil change/other maintenance/repairs, changed tires or wheels, etc.) or your commute? No accidents

The last 2 months the MPG has dropped significantly from the mid 40's to around 30. I know we live in the mountains, it is winter and we don't drive it only a mile to town. I have 95,000 miles on a 2010 Prius 3. I saw in some questions/answers discussions about the battery. Are we talking about the small battery on the right aft trunk or the battery pack. When I start from a stop, the battery pack doesn't seem to give it much of an initial start. I must admit that I didn't drive the Prius during the past few winters as we lived abroad and it was parked. Could my problem be in the battery? Would it be a good idea to have a computer diagnostic run on the car? Nearest Toyota dealer is 60 miles away so I don't just want to go there unless I can get some good info. Any advice would be welcomed.