What Language in "MPH" should we be testing at.
 

I was talking with a friend today about doing some FE testing and I told him that my plan was to run no faster then 45mph for the whole test so I could get killer results. He thought that was not a fair test, because most people would not run that slow.

He said it should be at 65mph because that's what people judge for the most part MPG. Plus he said it shows what the whole car is capable doing including the aero of the vehicle.

I would vote 65, also. My car starts to lose FE due to aero drag at about 68.
45 may be too slow, anyway, depending on where your peak torque is.

What are you testing, what point are you trying to prove, and for whom?

I agree. 45 would produce the best results, but 65 is a better speed to use if you want to find "real world" type results.

Testing all three of my cars but mostly my Honda.

My point is that you can make changes to your car to increase the FE over stock.

To show everyone that's interested in FE. But it seems like we need a common language or mph that people can relate to.

Question the A.M.E.C. runs. When I tell people about what their doing, the first question is why are the going so slow. So I explain the major advantages to running a car at 45 mph verse 65 mph.

Most people think that I should do my testing the way its known to the average car owner (city-mpg and freeway-mpg)

I'd say the biggest thing that people who aren't into hypermiling or modding for FE don't understand (or tolerate...) when speaking about gains is any time the car is either out of gear or moving with the engine off.

Leave it in gear, leave the engine running, prove mileage gains based on physical changes to the car alone (aero or mechanical)... then you'll have some believers.

I told a few friends about the HAI when I first did it and they were like, "Wait, you drove it normally. You didn't ever coast in neutral or cut the engine off and you got 43mpg... just from that HAI thing? DAMN! What's that car rated to get?" I told them 31 highway and one said, "can you help me build one for my car?" lol

When I do testing, I do it at the speed at which I'll be driving: 55mph (plus or minus a bit.)

In order to extrapolate the data to different speeds, you really need multiple data points. Some engine mods or general driving habits may scale linearly with speed... aero mods would probably not be so linear. For each change, a minimum of 3 data points (3 different speeds) would at least point to the type of scale to expect. Actual results will vary significantly from driver to driver and car to car (and with a whole slew of environmental variables.)

I guess it comes down to the fact that none of us are doing this in a controlled environment... there are so many variables involved that strictly controlling vehicle speed won't be enough to get repeatable/reliable results; we're ballparking it to the best of our ability. But that's NOT to say it isn't an important factor... doubling your mileage isn't actually that great if it only happens at 5 mph. =)

That is correct. I get readings from my scangauge that average about 35-40 MPG in my truck, but it only happens on flat roads when cruising at about 42-44 MPH. I can't do that on the highway. The best I can do at highway speeds is about 18-19 MPG. For this reason I actually get better mileage on 2 lane country roads than I do on the highway. I can putt down a country road at 2 or 3 MPH under the limit and not cause a safety hazard.

If you're trying to convince average drivers of a modification's efficacy, you should control your variables to match theirs as much as possible. That means driving like they do, the same speeds as they drive, same habits, etc.

Good stuff everyone!!! Thanks everyone for your input!!!

OK I think my next test will be at freeway speed and average around 65mph. Plus I'm going to have 4 different people drive the car for this adventure to take the driver out of the equation.

Re: What Language in "MPH" should we be testing at.
 

The A.M.E.C. runs are held on public roads. The courses includes stop signs and lights. There is a maximum time limit for the course to prevent drivers from going too much under the posted speed limit, but that time is figured pretty close to what the speed limits would allow anyway. The total time over the course distance might give an appearance of a low speed, but that includes high speed sections that offset the time spent at lights.
Not too bad considering lower MPG at higher speeds, and zero mpg when waiting to pull out from a side street into traffic. In my opinion, that 40~45 mph average yields a more realistic result than steady-state cruising at 65 mph.

Re: What Language in "MPH" should we be testing at.
 

I voted combined with an average because I believe it would be more realistic.

You could also do one at just 45 and another at just 65.

Just some thoughts.

Re: What Language in "MPH" should we be testing at.
 

I'm starting to think that the combine 45mph/65mph might be the only way to measure fuel mileage using a common language.

This will give us a great way to explain why at 45mph you can have extremely inflated fuel mileage numbers(driving skills,lower aero, etc) versus the
65 mph in which most people measure their fuel mileage.

Re: What Language in "MPH" should we be testing at.
 

When I got my Honda it tried to drive it nice and slow to only sip gas. To find out it didn't get very good gas mileage doing that.
Instead of 55-65 mph I started running it around 75 and mileage improved.
I'm sure it's the rpm that it likes given I live in the mountains. Too low rpm and it probably looses the efficiency while on a grade/ pulling hills.

Re: What Language in "MPH" should we be testing at.
 

It definitely differs from one car to the next.

Re: What Language in "MPH" should we be testing at.
 

On my Honda driving at 45mph the mileage improves a ton!!! Usually 8 plus miles per gallon.

On my wife's Toyota it doesn't improve much only a couple mpg.