MPG trials with different parameters

I'm running everything stock Prius II

First tank 468 miles, calculated 48.75 mpg, car was at 49
2nd tank was 434.5 miles (didn't go all the way to empty), calculated 48.165, computer said 51.1 mpg.

Its Florida, so our 'cold' mornings are in the 50's and 60's the last week, and 70's the rest of the time. 65-70's in the afternoon for my return commute. So I'm also not using AC more than to clear the windows.

I'm not sure the calculated is 100% accurate, as with the fill-up the first time I didn't try to put anything in after the first click on the pump, the 2nd time i put a little more in (as the pump had clicked 5-6 times on the first 5 gallons for some reason). With my old cavalier I knew exactly how far I could go on the tank and generally put in about 12 gallons (its a 12.5ish tank) so I had a good empty to full idea and it was easy to keep track of accurate mpg.

 

Hey Nine, good to see your MPG's goin up. Another suggestion might be to increase tire inflation even more to or near maximum per manufacturer recommendation which is @ 51 psi. That is the pressure mine came at & I have kept it at although my DSW is 225/45/17, we both should have the same psi spec.

Btw, my latest tank of gas was @ 46.9 mpg calculated. So, I'm getting about 4 miles consistently less than my stock setup.

 

Thanks for the info. That's not too bad. It falls in line with what some of us think the GenIII suffers from upsizing.

 

I used to run 51psi in my older Kumho 17s and they seemed to wear pretty evenly but after a few years one of them developed an out of round condition or something and I can not rule out high pressure being to blame or just old age.

I run my 15s at 50psi although they are rated at 44psi max.

 

+1 on the N-78 blend.

Don't bother with N-100. If somebody tells you there's a difference, they're either a dealer or a victim.

 

You're right, not too bad & although I wish I didn't have to lose the 4 MPG, at least it's being used for better handling & good looks, always good reasons for a compromise.

 

Agreed. I'm glad it works for you. I still can't get over the loss so I swap back and forth over and over.

 

Yes, I received it from Discount Tires Direct @ 51 psi & have since checked & kept it at that pressure. Curiously, all the wheel/tire came w/ a warning sticker labeled that it was inflated to maximum tire pressure(I just assumed they may have done it knowing that it was going on a prius but not sure as I never asked them about it). I would say inflate to at least 45 psi or more as it is still cool weather wise & I don't see any harm other than maybe a little more firmer ride. FYI, my stock Bridgestones came at 35-36 psi from the dealership. About a month after driving it, I couldn't get to 50 MPG. Than, I found & read up on some tips(inflation) on improved mileage on this forum. So, I proceeded to inflate to 38 psi than 40 psi(40 is max psi recommended by mfg.) & saw my mileage go up to 50 & beyond on every tank thereafter despite still being a fairly new prius owner & gauging it in winter time although I am in socal.

 

I may have to copy your system if I decide to go on long trips or for whatever other reasons as I have a 3 ton jack & it's quite easy changing out tire/wheels.

 

Don't do it man. Just sell the OEMs so you are no longer seduced by the allure of 55mpg tanks! She will get you in the end and you'll be back to boring old OEM styling........

LOL

I love the look of my big wheels but it's so much more fun to achieve big mpg numbers.

 

I agree, it is very satisfying & rewarding to my pocketbook getting high MPG, not to mention the fun(almost like a video game) trying to beat your past high mileage(MPG's)

 

I think you'll see some gradual increase in mpg in time. I know there are so many variables such as climate, traffic, mood & even luck(w/ traffic lights & type of people that are driving around u because if they're aggressive u have to accomodate some).
My last 2 updated fillups have been 47.9 & 49.1 calculated. I'm trying to get to 50 on my current setup.

 

My last 2 fillup update. 49.6 & 48.1 calculated.

 

Summer is just around the corner.... Better fuel is coming.

 

Haha, I was driving kinda conservative to try get to 50 & on 2nd tank I said f@@k it & drove more normal. You probably drive more aggressive than me. If I drove aggressive I would have a hard time getting 46.