One Tank of Gas, 847 miles later...

Cool thoughts, always nice to see someone who loves The P.

Not too sure on the diesel front though, you'd have difficulty hitting the same thermal efficiency numbers as the Atkinson cycled petrol engine, take a weight penalty (iron block, turbo, intercooler, DPF) and increase the BOM (turbo, intercooler, DPF).

 

HSI = 64.9 mpg

 

I think one of the keys for achieving higher MPGs is being able to run the car at efficient speeds. For example, your average MPH is 31, which would likely indicate a low amount of 70+ MPH highway driving. My average MPH for each tank is 49 or 50 due to my 80+% open interstate driving habits. Hence, my MPGs are at or below 50.

 

Amazing! I'm noticing, as the air temperatures are dropping, that our overall FE is down...and that the ICE wants to run a lot more often...even when it's only been shut off for a minute or two and there is plenty of battery power available. Still getting close to 50, which is awesome, but I know the cold winter will take a toll on that number, and it saddens me.

 

There is a real big hit below 36F. I am about 43 for the tank now. But I don't drop below that even when it is down below zero.

 

Man, do I try!!! I find myself saying "DAMN" every time I get on a nice straight piece of road where I can set cruise at 35/40 and someone comes from behind and starts riding my arse... I'd pull over to shoulder and let them pass but sometimes not possible. But, yes, I've found long stretches of moderate cruise controlling really yields great MPGs.

 

I have the same problem. My average speed for a tank with my typical commute is 47mph-50mph. I drive 95% or more highway at 60mph-65mph. This will net 47mpg-49mpg with the 17s and about 55mpg with the 15s. Or I just lose it and drive like a maniac for a tank or two and drop to 40mpg. lol

Good job to the OP. I've never pulled off better than 62mpg on a tank. I don't know that I have the commute or patience for such numbers.

 

do american prius get better mileage than Canadian prius ?

i'm only getting 550km a tank now

 

No. some people just have very good driving conditions and a lot of skill. The ones with very high miles on a single tank are using hypermiling techniques and they drive until the low fuel warning comes on and often beyond. Keep in mind OP was getting 64mpg. This fact helped him go much further on a tank.

In my GenII I can go about 450 miles on a tank at 55mpg. If I drive more after the low fuel light comes on I can go almost another 50-75 miles. I do not recommend this.

 

Wowsers! 847.3 miles! Congrats! :first:

You have guts... I've been too afraid to go too much farther than 700 miles.

Are you using 10% Ethanol blend gasoline?

What made you eventually decide to fillup the gas tank? :juggle:

Did the gas engine start to sputter as the Prius drank its last drop of gas?

Or did the onboard computer give you any kind of different warning other than the flashing single bar on the fuel tank gauge?

If 847.3 miles was your total distance for your fillup and you used 13.75 gallons of gas then you got 61.62 mpg calculated - which for November in Maryland is really good fuel efficiency.

I'd like to say that my scangauge suggest that the Prius gets a slight boast in FE if its hypermiled on the last two gallons of gasoline. My guess is that the decrease in weight due the empty gas tank puts less weight on the rear tires and therefore produces less drag on the rear wheels making the Prius *glide* longer in a P&G cycle. I suppose you could do the same thing by removing the rear spare tire from the Prius - but I've haven't tested that theory out yet.

One of the niftier things about the Prius is that the transmission is fly-by-wire so the transmission stick is nothing more than a switch. This means that when the driver is switching from Drive to Neutral and Neutral to Drive that there has basically no resistance at all when one is doing the hypermiling trick NICE. However, the Prius transmission stick has the short throw when switching from Drive to Neutral which means the driver needs to keep his arm steady to do the switching - it turns out that the driver's right armrest is useful in helping keep the driver's right arm steady while doing the switching back and forth from D to N and N to D when performing the hypermiling NICE trick. The most effective time to use NICE is when you have a long (>.2 miles) gentle downhill grade road with no stopping, your engine is already warmed up, you are going between 25 to 50 mph, and the battery SOC is over 50% - by shifting to N - the driver removes the internal resistance (of the ICE) on the wheels from the equation: Prius goes forward based on its momentum and gravity while the forces slowing down the Prius is tire/road surface friction and wind resistance. As you near the end of the downhill grade (or if the speed drops too low) you shift back to D and use the gasoline engine to increase your speed. The shorter they cycle (downhill distance) the more difficult this technique is to do. Also when the Prius is in N - the brakes still work but there's no regenerative braking (only hydraulic braking) so the most energy efficient way to stop the Prius is to put the Prius back into D to recover electricity via the regenerative brakes.


Walter Lee
(MD-DC-VA Metro Area Roads)
Mileage log "HyperDrive 1" on Cleanmpg.com
2010 Toyota Prius III, Blue Ribbon/Dark Grey, OEM floormats
Yokohama Avid S33 ( front 50psi/rear 48 psi)
100% lower grill blocked / 0% top grill blocked (temporarily)
ScangaugeII (Fwt, RPM, SoC, GPH)
Odeometer +17000 miles, overal MPG 60.9mpg

 

IIRC - over filling the gas tank means storing some of
the *extra* gas in the gas tank fuel venting system.
The venting system allows gasoline vapors to escape
if the gasoline is heated up (and expands) - fuel could
possible escape too. The OP's GenIII uses a regular/rigid
fuel tank but a GenII uses a lightweight bladder/expandable
fuel tank which makes the fuel gauge is less accurate
- hence the GenII general rule is to not tempt fate when
the low fuel light goes on is a prudent one.