Winter not good for mileage...

[trollbait]

Is the motor cycle air cooled? Could tough keeping it warm in cold weather. Even if water cooled, a motorcycle engine is more exposed to wind than a car's.

[SteveMak]

Originally Posted by gregsfc

...meaning it's about a 3% drop in fuel economy...

FYI, when talking fuel economy, MPG and percentages related to MPG are misleading.

Say for example we use 30 MPG (US gallons) as our baseline, and something changes so that we get 20 MPG, the difference being 10 MPG. Doing the math, we see 10/30=0.33, and so we (correctly) state our MPG dropped by about 33%, and we (incorrectly) believe our fuel economy also dropped by 33%.

When we measure fuel economy the the way around -- that being in L/100km or gallons/100 miles -- we reveal actual fuel consumption over a fixed distance, and that tells us the true impact on our fuel economy.

To use the same 30 MPG example, this number converts to 7.84 L/100 km. Let's compare that to the 20 MPG, which converts to 11.76 L/100 km. That's an increased fuel burn of 3.92 L/100. Do the math: 3.92/7.84=0.5, and we see a 50% increase in fuel burned for the same distance. So in this example, our fuel economy is not 33% worse. It's actually 50% worse.


This is an important fact to remember when we're shopping for a new vehicle, especially when we start with a pretty efficient baseline, and we believe we're doing a whole lotta good by getting 3 MPG more, when in fact, we're reducing fuel burn (L/100km or Gal/100mi) by a tiny and possibly inconsequential amount.

It's also important to know this when we are tempted to criticize fuel economy regulations, current or proposed. The 2016 "footprint formula" CAFE-required fuel economy for a small car (e.g., Honda Fit) is 41 MPG, and the proposed CAFE target for 2025 is 60 MPG. OMG!, some people say! That's 50% higher and unrealistic. However, if we compare the target 3.92L/100km to the 2016 baseline of 5.74L/100km, that's a reduction of 1.82L/100km, or 1.82/5.74=0.317. In other words, we're really talking about reducing fuel burn by 31.7% and not "increasing fuel economy by 50%." Reducing fuel burn by 31% over nearly the next decade looks quite doable, especially with what we've learned about hybridization.

[luv2spd]

Originally Posted by trollbait

Is the motor cycle air cooled? Could tough keeping it warm in cold weather. Even if water cooled, a motorcycle engine is more exposed to wind than a car's.

You can notice a big difference in horsepower and fuel consumption when the temperature drops. When I had my 2000 Kawasaki ZX-6R, it had a 4 cylinder carbureted engine that was liquid cool. When the temperature dropped from 77F to 30F; my butt dyno was telling me that I had about an extra 10% horsepower and fuel ups told me I was using about 20% more fuel.

When I had the 2003 Buell Firebolt XB-9R (air cooled, v-twin); the change was not as drastic. My butt dyno felt like I had about 5% more power and I used about 5% more fuel. The engine really wakes up when the air temperature is very cold outside, it's just a shame that the tires have no grip due to the cold and I can only ride for about 30 minutes in 30F air.

With cold air, the air is more dense so you are burning more oxygen, and with more oxygen more fuel burns producing more horsepower.

[AccentDave]

Originally Posted by SteveMak

Say for example we use 30 MPG (US gallons) as our baseline, and something changes so that we get 20 MPG, the difference being 10 MPG. Doing the math, we see 10/30=0.33, and so we (correctly) state our MPG dropped by about 33%, and we (incorrectly) believe our fuel economy also dropped by 33%.

When we measure fuel economy the the way around -- that being in L/100km or gallons/100 miles -- we reveal actual fuel consumption over a fixed distance, and that tells us the true impact on our fuel economy.

To use the same 30 MPG example, this number converts to 7.84 L/100 km. Let's compare that to the 20 MPG, which converts to 11.76 L/100 km. That's an increased fuel burn of 3.92 L/100. Do the math: 3.92/7.84=0.5, and we see a 50% increase in fuel burned for the same distance. So in this example, our fuel economy is not 33% worse. It's actually 50% worse.

I think you are mixing fuel economy with fuel consumption. Going from 30 mpg to 20 mpg is 33% worse fuel economy or 50% worse fuel consumption. Going from 20 mpg to 30 mpg is 50% better fuel economy or 33% better fuel consumption. Using L/100km going from 7.84 L/100km to 11.76 L/100km is 33% worse fuel economy or 50% worse fuel consumption. Finally going from 11.76 L/100km to 7.84 L/100km is 33% worse fuel economy or 50% worse fuel consumption.
Fuel economy is Dist/vol (like km/L or MPG)
Fuel consumption is Vol/dist (like L/km or gal/mi)
It gets confusing if the terms are switched.

[SteveMak]

Originally Posted by AccentDave

I think you are mixing fuel economy with fuel consumption. Going from 30 mpg to 20 mpg is 33% worse fuel economy or 50% worse fuel consumption...

If your perspective is that burning 50% more fuel means fuel economy is 33% worse, then I won’t argue with your perspective. I recognize that some habits are hard to break. It’s likely due to you always seeing “fuel economy” expressed as MPG in ads, government metrics, car showroom window stickers, etc. It’s what you’re used to.

My point is that MPG is misleading. Here’s an example:

Ted drives a gas-guzzling truck, which delivers just 10 miles per gallon (MPG), and his neighbor Joan drives an efficient economy car, which delivers 35 MPG. We applaud Joan for saving the planet, and scowl at Ted for driving a truck. This is our baseline.

We have motivated both of these drivers to get new vehicles to reduce fuel consumption and pollution. Ted buys another truck, which delivers 12 MPG, and Joan buys a new gasoline/electric hybrid car, which delivers an awesome 50 MPG. When we look at these numbers to assess each driver’s impact of switching to a new vehicle, we see that Ted is getting only 2 MPG more, while Joan is getting 15 MPG more, so we (incorrectly) conclude that Joan’s switch is doing much more good for the planet than Ted’s, not to mention the savings in fuel costs. It appears that she’s doing seven and a half times better than Ted (15 MPG more compared to 2 MPG More). We believe this because we’re looking at a misleading metric: miles per gallon. Similarly, if we compare Ted’s new truck to his old one, he gets 20% better MPG while Joan’s new care versus her old car gets almost 43% better MPG! Wow!… and misleading.

When we look instead at gallons per hundred miles (GPHM), then we’re able to perceive what is actually happening, gain a deeper understanding, and make a meaningful comparison.

Ted’s original truck consumed 10 GPHM while Joan’s original car consumed about 2.86 GPHM. After the switch, Ted’s new truck consumes 8.33 GPHM, a savings of 1.67 gallons of fuel for each hundred miles he travels. In comparison, Joan’s new car consumes 2 GPHM, a savings of just 0.86 GPHM. By using this meaningful metric, GPHM, we now see that the change in vehicles has Ted making about twice as much of a difference in reducing fuel consumption (and likely related pollutants) as compared to Joan. All this is missed if you use MPG as your measure of “fuel economy.”

But all this will be lost on some readers, specifically those who are locked into the MPG comparison, believing it is a meaningful metric for making fuel economy comparisons. And yet in the U.S. (and some other countries) “MPG” is synonymous with “fuel economy” in consumers’ minds.

[Draigflag]

MPG is a poor measurement, but like you say, most of us are used to it and know roughly how it translates into every day costs. For me, cost per mile is more important, and easy to work out, as you just multiply the "cost per litre" displayed at Petrol stations by 4.546 (the UK gallon) Divide that figure by your MPG figure to get cost per mile in fuel, and then depending what you want to know, it might be cost of a particular journey, or annual cost, you just times that by the miles driven.

Of course, fuelly does most of that anyway, but you get my drift.

[AccentDave]

It's just the definitions of the words it's easier if they aren't mixed (but that's probably just me). I guess it's my science background but neither is more confusing or "better" from my perspective they are just the inverse of each other.
FE = fuel economy
FC = fuel consumption
FE = 1/FC
FC = 1/FE

[R.I.D.E.]

Hit 57.9 (US = 69.5 Brit) this last tank, with refill at $1.949 per gallon, $10.95. Divide the fill cost by the miles 1095/325 = 03.369 cents per mile. Warmer here lately, versus below 15F a while back. Picked up an extra 5 gallons since it requires me to drive into a 20 lane intersection to get to Costco.

Traffic here is lowest this time of year, many opportunities to extend glides without someone climbing up me arse.

[14Corolla]

I'm continuing to get verification of what was discussed earlier in this thread.
Just have to face the fact that winter is bad on mileage.

I did just find out. I may be changing where I go to work. That will change apparent mileage. It will go up. Right now, I have a big hill to climb immediately when leaving the house. In winter with car cold, it really sucks the gas. When I change, I'll be going the opposite direction. Won't have that hill to deal with. Will be doing highway mileage for about ten or fifteen miles. No more mileage sucking 5 miles to work when it's cold out.
Also this is one year owning this car. Spent $482 for one year of fuel. Can look at my dashboard for other details. Have more often fuel ups in winter. Keep tank fueled up when it's cold. Don't let it get much below 1/4 tank. That's probably another addition to bad winter mileage.

[R.I.D.E.]

One thing I noticed was my EOC (engine off coasting) headlights getting dim, so I hooked up my 4 amp trickle charger yesterday. It took until this morning for it to top off the battery completely about 7 hours all together. Today with the topped off battery I hit 72 mpg on one leg of todays driving over close to 20 miles through Williamsburg very near William and Mary.

My mileage is hanging in there in spite of Winter, but it takes more concentration and situational awareness to keep it that high. Also I drive the truck when the weather is lousy.