After Break in Period = Better Gas Mileage?

My fuel economy has improved over time. Some of it is mechanical (blocked grill, harder tires). Some of it is learning to drive better (changing route, driving slower). Some of it may be the car settling down. Some of these changes are conscious decisions, others you won't notice until after they happen. Change what you want and just enjoy driving the car.

 

I have noticed an improvement in mpgs after the car passed 4,000 miles. There probably will be another improvement around 10,000 miles as well. One downside though is that the winter gas blend in the S.F. Bay Area has screwed me on mpgs. Until about October, I was getting a consistent 48 mpgs in mostly highway commute. Now, I am getting something like 44 mpgs for the same commute.

 

Just putting a few hundred miles on your tyres will improve mileage.
A few thousand and piston rings will bed in, seals become free sliding, oil coats everything permiating the metals, oil viscosity drops, even the water pump drive belt settles in and moves easier. High spots come off the break linings, throttle valve moves smoother and you as a driver become smoother.

Great economy comes to Prius owners with patients.

 

I didn't notice any significant improvement. I drove 1300 miles in the first 4 days of buying the car, and we averaged about 51 mpg (68 mph). 15,000 miles later, I still get the same, even with my tire pressure is higher than before and I know how to P&G etc.

 

If your car was my car, I am a very happy dude. 51 mpg ain't bad at all.

 

Maybe it's the result of Happy Hour at the bar here in the hotel but I'm not quite sure of the source of your disappointment. As I recall you were exceeding the EPA number and now due to conditions have taken a 10% hit. I suspect every other car also takes a 10% hit. The only problem is that 10% of 50 is much more noticeable than 10% of 25. Exterior factors have a greater influence on the Prius than on other cars. Simple & cheap things help. In NY you should have the grill blocked and an EBH. Increasing the tp also helps. BTW I know how you feel. Now if I could only get my average to 55...

 

I've noticed a marked increase in FE now that my 2008 has around 2600 miles on it. I'm now consistantly getting in the 54-56 range which includes some highway driving at >65 mph. It also doesn't hurt that I live in Phoenix and the temps have been very mild this winter (we just had a snap of 4 or so days in the upper 70s).

All in all, I'm hoping for another bump around 10K miles...

--
cf_coder

 

i am getting 51.2 on my mfd on my car here in the bay area with about 500 miles on it. my fiancee says she gets 50.1 on hers now in southern california with about 1100 on it. i put in 400 miles in that thing while delivering it to her in l.a. and got 48mpg on the mfd averaging 75-80mph but filled it up and calculated to be only 43.6.

 

You can't calculate mileage in the Prius like you can on other cars with a solid tank. You can keep a log over time and it should match the MFD closely, but individual "fills" are not the same. Because the bladder in the tank changes with temperature (air and gasoline), you may get less in your tank this time than you burned since the last fill, messing up your individual calcs. In the case of a single fill, the MFD is much more accurate.

 

You lost me on this one...there is a bladder in the tank that changes sizes?

 

Yes. It's probably mentioned in the owner's manual, in John's user guide, and many threads here.

 

But I haven't heard where the bladder changes the volume of liquid (gasoline) that the tank holds. The bladder is an evaporative emission control measure. It does not 'change' the storage capacity of the gas tank itself.

 

not sure how the computer calculates MPG, but in my 2004 Sienna, the "computer" tends to state about 10% better mpg than when calculating the old fashioned way...So, anyone haev any idea just how accurate the Pirus computer is for mpg?

 

I wondered that too, until I saw a post where they had pictures of a gas tank from a parted out Prius. The best way I can describe it is you have a metal framework with a stiff rectangular tank; the walls near the top of the tank are accordioned so the top can rise and fall. But it's affected by temperature changes (gets stiffer when cold) so the capacity is usually less in the Winter months. This effect will also make it seem like your gas mileage is improving in the Fall months, until you run out of gas one day like I did! Right now the weather starting to turn warmer, and it looks like my mileage (from calculating fill-ups) is worse that the MFD says.

 

soooo.. is the mfd actually fairly precise or just and average of overall mpg's?? (if I asked that right).. I'm just hopin that if the car shows me getting @ 50mpg over like 4 tank fulls, then I hope the manual way of averaging (over the same 4 tank fulls) would match... That way it takes the single tank inaccuracy out of the equation... Is this correct? Are the MFD's correct?

 

You might be able to make a case for a replacement gas tank because of the temperature effect on the bladder reducing its effectiveness as an evaporative emission control.

 

I am currently in Portland, Oregon. I have noticed a huge drop in fuel economy this winter. I typically have a 5 mile drive to work. In cold weather (~40 degrees) I get about 34-35 mpg. On a longer drive (15 miles) I get about 45 mpg. I have tried a blocked grill and more air pressure without much improvement. Has anybody else had similar low numbers in short distances in the cold? I do drive conservatively as it is.

 

You might want to consider a block heater.