Qs: Maintenance while driving little; declining gas mileage

1. Toyota says to do the maintenance at the miles or months, whichever comes first. This kinda falls apart if your car is practically mothballed, but with your miles I wouldn't say you're there; I would play by the rules.

2. Consolidate trips wherever possible. Also, if it's a toss-up: say shopping at a local store, vs driving to a mall, go with the first whenever practical. Give your local merchants some business. These two tactics likely mean the car sitting even more, and it's worth considering a auxiliary charging system for the 12 volt battery.

3. Unless you're noticing something odd with the steering, recently hit a curb hard, uneven tread wear, something like that, I'd leave it be.

This is our scenario in spades btw: last time we drove was Monday a week back, fridge and cupboards are well stocked, and the car's sitting on a charger.

 

once a year oil change is fine

new tires reduce mpg's until they are broken in, unless they are not LRR and rated for the same mpg as the ones replaced.
alignment is only necessary if the car is not tracking straight, or the old tires wore unevenly.
winter gas will effect mpg in california.
as mendel stated, short trips will kill you, and time between drives can deplete the 12 volt battery, then the engine has to run to top it up.
make sure the new tires are properly pressurized, and check/clean/replace the air filter

 

I've noticed in my Gen 2 Prius if I don't get a good long freeway trip with cruise control on every once in awhile, gas mileage will slowly decline.

Try and get a 30 minute+ freeway trip in at 60-70+ mph and see if your mpg improves after that.

Posted via the PriusChat mobile app.

 

Short city drives involving hills will definitely reduce your average MPG. Cold weather/heater needs also take a toll. I see 10 MPG drop typically between summer and winter conditions. The reduction you're seeing, in the 40's now, makes sense given your changed driving conditions. New tires can also reduce your MPG, especially if not "eco/green" low rolling resistance type.

 

Our 2010 has the block heater, and we try to plug it in 2 hours before any cold start. This helps a bit with the short trip mpg, and I think it's beneficial for engine "well being" too.