39 MPG - Any ideas?

Yes, 39.5 mpg is not too flash--47 or above would be better. I don't see anything that stands out amongst the usual suspects.

You are not clear on what tires you now have on the car, they can make a difference.

What kind of terrain do you usually drive? Is it hilly or mostly flat?

How do you measure the MPG--the MDF or do you calculate on fill-up? If you use the MDF and do not keep records, you should start to use a site like Fuelly, as you can work some things out by looking at your history. Relying on your memory is just asking for trouble as people tend to remember details a little too subjectively, which makes for some very bad conclusions.

Let us know the answer to the above questions and then we will see where that takes us.

 

Your mileage does seem low, highway driving at 55-60mph should still yield more like 50mpg on a Gen 2.

How long is your typical trip? Short trips will generally yield lower mileage due to the warm up cycle.

How did the wear look on the tires you took off? Pretty even across the tire, or lopsided?

The first things that come to mind beyond what has already been asked and what you've already done are wheel alignment and/or brakes dragging? Wheel alignment might show up in the wear pattern on your old tires. Brake drag might show up as an excessive amount of brake dust on the offending wheel.

Best of luck,
Rob

 

should have bought some LRR tires. I wouldn't really want to put any Korean or Chinese tires on my car.

 

the tyres are probably costing you 3-5mpg. where are you located? best test for the 12v is a voltmeter on the battery after it has been off for a few hours.

 

As far as I can see those Kumho tires are not LRR, so that will be costing a few MPG's.

If your daily driving is taking you up and down hills on shortish trips, even if the change in elevation is only 100-200 ft, then that will be keeping your MPG's down too.

A good exercise would be if you can do a test run of 20 mi out and return back to the starting point on a highway that is relatively flat. Reset the average MPG gauge on the Consumption screen before setting out. Set the cruise control at 55 mph (if possible) on both legs and then report the average MPG reported on the Consumption screen at the end of this exercise. (Warm up the car completely before starting this exercise.) This will give a baseline that will give us an idea of whether there is any problem that may require further investigation. If doing that is possible and interests you, let us know how you get on.

 

how many miles on her? i'm thinking 10year old car, bad tyres, eliminate the 12v as an issue, and it's probably a matter of wear and tear, just a lot of little things including the hybrid battery, fuel system and etc. you might consider the priuschat shoppe, hybrid battery re energizer. (grid charger)

 

Per Bisco the 12v is what we always say.
Make sure the tires are standard size otherwise there could be a correction factor due to revs/mile.
In that climate situation we like Ecopia 422 or Energy Saver A/S for best MPG.

 

12.3 is borderline bad. i can't guarantee it will improve your mpg's, but i would replace it anyway, before you get stuck somewhere with a no start situation.

 

It is a well documented fact and I appreciate what you are saying. However, it is relative and would still be a useful exercise. The results would be (relatively) meaningful, but ultimately it is your call.

 

12.3 V is basically completely discharged. If you have a battery charger, you could try fully charging overnight (12-16 hrs) and see if your battery responds. But my gut feeling is that if your battery has been in this poor state for some time, then it probably is irreversibly damaged.

 

Couple more things you can do to try and improve your MPGs:

- Spark plugs
- MAF cleaning

I've had mine for a little under a month now as well, and drive 42 miles round trip, mixed city-highway and get an average 50 mpgs.

 

I have put many sets of Kumho Solus on with good results. There are many different Kumho Solus KH16, KH25, KH26, KR21 etc. Although they are not branded as a LRR most of them have a reasonable tread pattern for smooth rolling and are light weight under 18 lbs. Which model do you have?

I may have missed it but how many miles are on your car?

1. Check/change if necessary spark plugs
2. Clean throttle body
3. Change transmission fluid
4. (x2) Grid charging may help and will extend life of HV battery