Fuel consumption issue

Sounds like you bought the tank not a Prius

25 l/100km = 9.4 MPG [US]!!

I believe the unit on your display is [km/litre] - then it makes sense. And the result is pretty good.

 

Yes, the Japanese use km/l. Do "by hand" calculations to confirm when you fill up - record mileage when you fill the tank (and fill it the same each time). The second time you fill up use the distance traveled and the fuel you put in to calculate the mileage. The reading on the dash is not accurate. It's an "estimate". Even the above method will give erroneous numbers. Only after 3 or 4 fill-ups will you get really close.

 

The 12 volt battery is a good place to check, if it's going bad, so will your mileage.

 

If you are currently getting 58 or so miles per gallon (this is a unit im more familiar with) then you are at the top end of casual driving fuel efficiency for a prius. If you want to ever do any better than that you need to be very meticulous on your gliding and implement all types of hypermiling techniques carefully. But you are currently doing very well so I wouldn't expect too much more if you travel for a living, and especially if ever do any highway travelling.

Edit:
Oh I see you say you are currently getting 18 or so kilometers per liter, which yes is very poor (about 42 mpg). If this is something that doesn't seem to get better with careful driving, then it definitely seems like something is very wrong. Keep an eye on the efficiency meter and try to keep it pinned at the top as often as possible.

 

OK, you seem very knowledgeable, but I have to ask, are the tires inflated to a high enough pressure? I have mine at a compromise pressure of 38 psi front, 40 psi rear. 40/42 was a little too rough.

 

Reverse your pressures to 40 front, 38 rear.

 

Regarding the new tires: Did you install LRR tires or are they standard tires? This can make a signification difference in fuel mileage.

 

has it gotten colder where you live?

 

^ That. I easily get 48+MPG average in the warmer months, but I'm happy to get even 34MPG average in the colder months. Worse yet, I drive only one mile to work and back, which destroys the mileage even more.

Length of your average trip?

Seasonal temperatures getting gradually colder?

 

Good to hear. Sometimes I forget to check the most obvious things.

 

i would suggest the thread "fuel economy complaints/queries", it's a sticky in gen II forums. posted by cwerdna. all the best!

 

Not too bad. That's just a little over average in the US. Personally I put about 50K km (just over 30K miles) on my car last year, but many people have it way worse than I do.