Top 20 - MPG Record Holders

My Prius is at the 1/2 tank level, the trip odometer is at 390 miles, the MFD at 73 mpg, and my MTE at 290 miles.
Because the driving temperatures have dropped below 6o F degrees - I started grill blocking
At the very latest - my next fill up will be Friday September 28th.
After September, my Prius mpg start dropping as the outside temperature drop
- so this will likely be my last tank this year where I still can do +70 mpg.

 

Ya, from the sounds of it (haven't actually experienced a winter in a Prius yet) this will be my last 70+ as well. I'm just hoping I don't have too many in the 50's.

 

FWIW In my 700 mile tank I encountered the flashing last pip about 30 miles from the gas station where I began. I will admit to some nervousness as I have always filled much earlier and this was my first experience dipping this low into the tank. The fill was 8.59 gallons, apparently leaving the better part of a gallon to go, so I won't be quite as nervous next time.

I still do not know exactly how much fuel I can put into this thing. Short of running to empty I only have the experience of others to go by. There are a couple of threads in the c forum where claims are made of fills from just over 9.5 up to 10.

I have read elsewhere that tank capacities may vary slightly within a given model due to manufacturing variables. So .....

 

I'm not sure how "tank capacity" is defined. I do know, from reading other threads/posts, that people do have the ability to "overfill" their tanks which is usually referred to as "filling it to the neck" such that you can see the petroleum. It appears you can add an extra 1.5 - 2 gallons to the Prius Liftback's fuel tank by slowly pumping, ignoring the fuel vapor pressure locks/shut offs.

This probably has more to do with the varying fuel fill ups/max capacity people report rather than manufacturing tolerances of the fuel tank.

 

http://dps.sd.gov/licensing/weights_and_measures/images/Fuel%20Tank%20Capacity.pdf

 

A good read. So tanks may have up to a 3% error due to variability in manufacturing (thus a 10 gallon tank may be 9.7 gallons or 10.3 gallons. However, people can easily add more than 0.3 gallons by continually pumping gas into the tank (after initial shut off) displacing the air pocket above the tank. With my car, I know that after the initial shut off (assuming nothing is wrong with the pump's vapor lock system). If I repump gas into the car, I can add about 0.25 gallons (+/- 0.05 gallons) into the tank. I did this for the first 2 years I had the car, because I wanted to have consistent fuel fill ups (not dependent on a pump that may have prematurely shut off). I've stopped doing this as it appeared that the fuel pumps I've used have been consistently good at shutting down.

 

Comparing 17 fuel-ups to 130 is no comparison. That's like filling your tank, resetting to zero, driving slow for a mile and cooing about getting 99.9 mpg. We'll compare again when you hit 56,000 miles.

 

Just start posting to the fuelly car that previously had the 17's.

 

"real winter weather" haha
How cold does it get there?

 

The Prius' MPG benefits from grill blocking early in the Fall if the Prius is primarily driven at low speeds (<45 mph).

When the trip is going to last longer than 7 miles/30 minutes it pays to warm up the engine sooner than later because a warmed up Prius is more FE- so atleast during the first 5 minutes of driving the Prius is better off in Normal or Power mode than in Eco mode. The reason a warm up the Prius ICE is more FE is because if the ICE is not fully warmed up the Prius will limits the length of how long a driver can induce a glide/coast which turns out to signficantly impact the Prius' overall FE for that trip.

My first winter (2010 Nov - 2011 Mar) was really cold and I was just learning how to hypermile in the winter - MPG dropped from a high of 66mpg in the Summer of 2010 to 52 mpg in the Winter. The Farmer's almanac forecast that California ( and the western regions of the UsA) will experience a mild or normal winter for 2012-2013. Last winter ( 2011 Nov - 2012 Mar) was mild for the DC Area so my MPG never dropped below 58 mpg.

 

If you time shift your trip when there isn't much traffic on the freeway there is a chance you could run the Prius with a 65 mph to 45 mph P&G cycle. My experience has been that even with a fully warmed up ICE that without a substantial amount of initial momentum (e.g. initial speed is +65) to sustain any speed over 50 mph without a downhill grade or a tail wind the Prius needs the ICE running at a minumum RPM [(e.g. HSI display indicator is approximatedly in the center OR ScangaugeII xgauge ( GPH=.50-.70, RPM =996-1200 )] - with the HV battery SOC at +60% the electric motors are fine at sustaining the Prius at about 35 mph for quite a long time. However, the HV battery SOC must over 55% before the electric motors have enough power to sustain a highspeed P&G - that is you need to have atleast 5 if not 6 bars on the HSI SoC HV battery display. It's the higher current/power levels of the Li-ion battery pack that really makes the electric only hi speed operation of the PiP possible and conversely it is the naturally lower current/power levels of the NiMH battery pack that limits the electric only hi speed operations of the regular Liftback.


BTW: I accidently reset the A trip computer so I won't be able to qualify for a higher MpG for this tank.
I have a slight chance of getting about 70 mpg (calculated) from this next tank (which I hope will raise my Fuelly average to 60.9 mpg) but l albeit I doubt I'll get +72 mpg (calculated) from this next tank - bad weather (i.e. more rainy days) commutes is causing my FE to drop.

 

Walter, please explain more about your theory of running the car in power mode for the first part of the trip. I'm intrigued.

 

Not a theory - just something that seems to be working out for me.

I've notice that during the winter when I try to pulse and glide too early - the ICE will take longer to warmed up because I am not running the ICE often enough to get the ICE up to its most FE temperature (180-190 F degrees) - during the initial part of the trip during the winter anytime I am using the ICE (e.g. for pulsing) the ICE tends to burn more gas ( e.g. iMPG lower for a given iMPH) because it is not hot enough ( coolant is less than 160 F). If I start from the get-go to aggressively hypermile in a winter time urban -suburban driving environment, it may take up to 40 minutes/10 miles from a cold start before the coolant temperature goes pass 160 F. During that time the gliding is more difficult and ICE burns more gas because its not warm enough. When the outside driving temperature drops below 60 F, if I run the Prius ICE more frequently (i.e. use Power mode / run the ICE more often) during the first 3-10 minutes (i.e. the first 2-4 miles after turning it on from a cold start) - I can accelerate the warming up of the ICE coolant temperature past 160 F (albeit the AVG is initially about 30 mpg during this warm up phase) - and then afterwards start aggressively hypermiling if this aggressive hypermiling segment of the trip is long enough (for example - over 12 miles) then I can nudge the Prius into getting better MPG overall results. What's going on? For a given outside temperature the Prius must burn enough gas to just get the ICE warm - my grill blocking does not significantly reduce the amount of gas needed. However, my grill blocking does help the ICE retains its heat so I don't have to constantly put more gas in to keep the ICE warm once the ICE is warmed up and that's when hypermiling can help improve the Prius' MPGs. This all sounds counter intuitive doesn't it?

 

So even if all this is true, it doesn't really have anything to do with Power mode, just gas consumption early in the drive.