Fuel Economy Top 10 Tips in order of % effectiveness?

I like where you are going with this. I also admire your guts to put numbers to it knowing that some are going to argue values. LOL

 

I haven't put a lot of thought into your chart or looked at the values, but how about trip length? Short trips will definitely kill mileage, esp. in short city/stop and go drives. If you trip is only so long, there's really nothing you can do. Making it longer might increase total fuel consumption, which is no good. Getting higher mpg values by using more fuel is a dumb.

However, if a trip has multiple stops, in some cases, one can optimize the trip to go to the furthest point first. That way, the engine is warmed up or closer to being warmed up vs. always not being quite warmed up followed by a cooldown period at each stop.

Back to warmup, there's the use of an engine block heater and grille blocking. I certainly wouldn't do grille blocking in the summer, but an EBH should be fine even now. Unfortunately, EBH isn't cheap, whereas pipe insulation to stuff the grille is.

OTOH, the heater usage can be a big deal in winter since the ICE can run to provide requested cabin heat, possibly running the ICE unnecessarily, in cold weather, wasting fuel. I discussed heater management at Why mileage gets worse in winter | PriusChat. (I've been too lazy to update that thread, but will do so before the coming winter.)

 

Driving in D will yield better MPG than N, B, R or even P.

Unlike other cars, N does not disengage any gears, it just does not power the Motor/Generators, try to stay out of N, as it can't charge the HV Battery.

B is useful in conditions where you would use L in a typical Automatic, down long descents. B gets worse mileage than D, but if the downhill is long enough to fill the HV Battery, then it is safer than D.

Since the engine always pushes forward, R gets worse mileage than D.

 

cwerdna is correct - short trips can cause the MPG of a regular Prius to drop like a rock AND the driving environment is a big FE factor [ e.g. driving temperature. Smoothness of the road. wind speed and direction. traffic. fighting gravity by going up uphill. working with gravity by going downhills. speed bumps. Rain. snow. ice. stop signs. etc. ]. Using 10% ethanol gas instead of using 100% gas can effect your MPGs too - albeit that may not be politically correct to notice... .

There are three hypermiling components in maximizing FE -

1. optimizing the distance generated by momentum (linear/circular)

a) minumize rolling resistance
(1) overinflate tires by +7 psi
(2) use Low rolling resistant tires
(3). drive on a dry smooth road

b) decrease aerodynamic drag on car,
(1) optimal speed is between 25mph to 55 mph
(2) eliminate unnecessary drag: e.g. bike rack or ski rack or roof top carrier.

c) decrease weight which initial inertia must be overcomed

d) minimize momentum loss via centrifugal forces by turning at lower speeds

e) drive when there is no traffic on the road
(1) drive during non rush hours
(2) drive when traffic lights are turned off ("flashing Yellow" mode)


2. optimizing the distance generated by gravitation (potential) energy.

a) gain speed on the downhill, the best routes have long downhills segments

b) lose speed on the uphill, the best routes have short uphill segments

c) avoid stopping at the bottom of the hill - try to stop at the highest potential energy location


3. making your vehicle power plant as energy efficient as possible

a) grill blocking when temperatures drop below 60F

b) avoid using climate control / defroster when possible

c) use 100% gas over 10% ethanol gas

d) drive when the outside temperatures is from 60F to 90F

e) drive when the transmission is in D mode, avoid N and B

f) Minimize the time and energy used by the power plant
(1) keep the *pulse* as shortest as possible in the most energy efficient range
(2) extend the "glide" time as long as possible where the power plant is off

 

^ I do the same.... It works great as long as you don't forsee yourself braking in the immediately afterward...

 

In engineering, we go to the lab and test. So here is the challenge:

Source: Double Tank Mileage Contest | PriusChat

Take your post in this thread to make your entrance posting in the contest. Then when you've achieved twice the EPA tank, following your own recommendations, take a photo of the trip meter. There is a handicap scale for 2001-03, 2004-09, 2010-current, Prius c and Prius v models.

Bob Wilson

 

Using pure gas with no ethanol will easily get you 3 mpg or more. I got a full tank in Reno several years ago on a summer vacation when we first got our 2010 Prius. MPG's went from 53 to about 58 mpg if I recall.

Here in Oregon we are mandated by law 10% Ethanol in our gas. Ethanol the only negative energy fuel....

 

Pure gas ought to get you closer to 3% better, not a whole 3 or 5 mpg.

The elevation at Reno, 4400 feet, helps all by itself without any fuel change. The 15% thinner air (compared to sea level) cuts wind drag significantly.

If you want to compare mpg of E10 to E0, be sure to do the tests at the same elevation. If you live at sea level, E0 should be available from some marine fuel outlets.

 

Good point about the elevation change. E0 is available over in Chinook Washington across the Columbia River via the Megler Bridge. Last time I checked Its around $4.50 per gallon, Costco in Warrenton Oregon is about $3.769 per gallon for regular 10% Ethanol. Too much of a price differential...

 

Gliding all the way to a stop won't get the absolute maximum anyway. Merely having the car ON and READY consumes several hundred watts of overhead, even when the car is stopped or barely creeping. The final energy salvaged by gliding all the way to zero won't cover the overhead in those last moments.

For steady speeds, research on this continent put out graphs showing the GenII's peak efficiency occurred somewhere between 10 and 20 mph. Japanese hypermilers who produced simple empirical equations for the power used at various speeds, came up with linear model that peaks very close to 15 mph.

I haven't thought about this enough to figure if this also means the minimum useful glide speed is 15, or something lower. But regenerative braking stops at 7 mph, and I see no reason to try to glide in slower than that. And of course, all this put zero value on one's own time.

As for the risk of getting shot, I'd suggest moving away from Chicago. Any random location in North America, north of the Rio Grande, should have a 98% probability of lower risk.

 

<AHEM>

Bob Wilson

 

Is that Sake or Bud in your glass?

 

Sorry, I forgot this chart, despite having seen it many times. I was thinking of some published white paper, possibly an SAE report possibly linked in one of your posts long ago, and an item from ken1784 (ken@japan), SuperMID designer.

 

No problem as I've been looking for a reason to play that tune. <grins>

Just a refresher, the EPA has a database,"Test Car List Data Files", that has the roll-down coefficients:

• drag_force = Target_C * (v*v) + Target_B * (v) + Target_A
  • v = velocity in miles per hour
  • Target_C (lbf/mph**2) - aerodynamic drag
  • Target_B (lbf/mph) - rolling drag
  • Target_C (lbf) - in effect, the vehicle overhead

Use basic physics definitions of energy and power and you quickly calculate the drag power needed at any given speed. The rest is the engine and drivetrain efficiency. Warning, there are a separate group of "Set" coefficients but this is what Ford screwed up for the C-MAX values.

Bob Wilson