-10 mpg!

[oldtamiyaphile]

Originally Posted by SDMCF

With you it is always summer!
Seriously though, why do you lose MPG in summer? Air con? What else?

It's pretty much a double whammy of using the A/C. I drive only city miles and here diesel are still sold without DPF's (until late this year) and our best/2nd best seller is the Toyota Hilux, so I always have the fan on recycle, it doesn't take a very hot day to need the A/C. When it's 35*C+ the A/C takes a lot of power but also means I can't EOC or engine off at lights etc, on a 40+ day it can mean a 20% fuel economy hit.

One of the reasons I bought a Prius is because the A/C runs off the HV battery, so the A/C hit is very, very small. I haven't had it that long, but I've found that improved warm up in hot weather roughly equals the added energy use of A/C.

[96CX]

Between winter gas and my studded snow tires, I lose about 9mpg in the winter. Summer, I average about 45, and then there's a stark drop to about 37-38 as soon as November hits.

[star_deceiver]

On average, I lose about 1.5mpg between summer and winter mileage. The worst mileage I've ever had come when the temp dips below -30. Snowstorms,4wd, studded tires, avg speeds of 75mph in all conditions doesn't affect mileage near as what stupid-cold air can suck out of the tank.

[SDMCF]

Originally Posted by star_deceiver

On average, I lose about 1.5mpg between summer and winter mileage.

I am impressed with that, especially in your climate.

[ciderbarrel]

Originally Posted by SDMCF

I am impressed with that, especially in your climate.

MPG is not linear, so that figure is meaningless. Let us assume he dropped from 16.5 MPG to 15. That is a drop from 6.06 gallons per 100 miles to 6.67 gallons per 100 miles. He is consuming 0.607 gallons more per 100 miles.

That inefficiency is the same as someone dropping from 50 MPG (2 gallons per 100 miles) to 38.358 MPG (2.607 gallons per 100 miles). This 11.642 MPG drop is the same as the 1.5 MPG drop from above.

[SDMCF]

I consider a drop of 10% or less to be impressive. Certainly significantly better than my own efforts in a similar climate.

[Fat Charlie]

My drop is over 20%.

[ciderbarrel]

Originally Posted by SDMCF

I consider a drop of 10% or less to be impressive. Certainly significantly better than my own efforts in a similar climate.

That is almost exactly a 10% drop (10.017%)

[star_deceiver]

Originally Posted by ciderbarrel

MPG is not linear, so that figure is meaningless.

MPG may not be linear but it is easily measurable whereas drivetrain inefficiencies, tire drag, snow density, headwind speed, air temp over distance and how they affect different vehicles and such are not...

For instance: It was 10C degrees today (Chinook). I used no 4wd. I drove 120kms with the 650lb quad in the box. I'm using 0w30 synthetic oil in the 4.8L v8. The transmission is a 4L60 4 speed auto driving a 3.42 rear end. The winds were from the west, between 15 and 30 km/h. The road was all Hwy at speeds between 100-130km/h headed west to the frozen lake. The Ecometer says that for this tank (240kms so far) I'm averaging 15.1mpg (generally it reads 0.3mpg low). Yesterday it was 3C degrees, same distance but with a different quad in the box, lighter winds. The tires are Nokian Hakkapeliita 8 SUV 265/70-17 studded on steel rims. Warm up time for both trips, to and from, was about 30 seconds from startup to driving.







Now, for this tank, IMO the biggest inefficiencies are the aerodynamic drag caused by the quad relating to vehicle and wind speed.

[ciderbarrel]

Originally Posted by star_deceiver

MPG may not be linear but it is easily measurable whereas drivetrain inefficiencies, tire drag, snow density, headwind speed, air temp over distance and how they affect different vehicles and such are not...

My biggest bugaboo is when people exclaim "This saved me 5 MPG!" Ok. Great. But what does that really mean in real numbers? Someone losing 10 MPG from 100 MPG to 90 MPG is increasing their fuel usage as someone else going from 10 to 9.89 MPG. 10.0 = 0.11? That is the MPG myth.


That MPG myth is one reason the EPA is adding gallons per 100 miles on new car stickers, since that actually shows a linear rate of fuel consumption.