Study: roof racks waste 100 million gallons of gasoline a year in the U.S.

[Fat Charlie]

I had a 96 Suzuki Esteem sedan that got 40-42 mpg. I didn't log back then, but I calculated at every fillup. I tied a Christmas tree to the roof and drove 2 hours on the interstate, got 20 mpg for the trip.

[Frank Lee]

Originally Posted by carolina guy

Agreed...was reading just before putting the kids to sleep and haven't updated in a while. Although before one calls BS one "should" have all the information, eh? :-). Short fills are accurate to get the highway portion that I was mentioning...the city only usually yields around 15 mpg in my experience around Charlotte either light or heavy footed.

My gas log on my phone shows 17.2 mpg city / highway over the last six months / 5500 miles tracked. That includes a lot of non commute local driving and getting mulch, lumber, rock, etc while hauling the wife and 4 kids instead of just myself on the highway with cruise control.

BTW: this is without turbos...just the old Vin W 4.6 auto with 233k on the clock.

Short fills introduce large fill errors into the calcs. Unless there are enough entries to average those errors out, they are... well... prone to large error.

Even on a proper "full-fill", one tank does not a valid claim make. See: Sport Coupe.

I have all the information I need to make my call and you will not prove 21+ mpg at 75 mph. Your gas log shows a believable 17.x.

http://ecomodder.com/forum/showthrea...tml#post182705

http://ecomodder.com/forum/showthrea...g-16344-2.html

[Xist]

I filled up my dad's F150 one time, 19 MPG at 55 MPH. That is hand-calculated. Factory gauges are often at least a couple percent high.

[carolina guy]

Originally Posted by Frank Lee

Short fills introduce large fill errors into the calcs. Unless there are enough entries to average those errors out, they are... well... prone to large error.

Even on a proper "full-fill", one tank does not a valid claim make. See: Sport Coupe.

I have all the information I need to make my call and you will not prove 21+ mpg at 75 mph. Your gas log shows a believable 17.x.

http://ecomodder.com/forum/showthrea...tml#post182705

http://ecomodder.com/forum/showthrea...g-16344-2.html

Again, I will have to give your "call" a (*shrug*) as being worth what I paid for it. :-)

But FWIW here is some logging I have done with my SGII (after installing the dual efans) over the last week (cannot find the other paper I was using before the spreadsheet) so this will have to do.

This is for a 43 mile each way commute using primarily I-485, I-77 and NC Hwy 49 in the Charlotte/Cabarrus County area. The speed limit for I-485 is 70MPH and it is NOT a good idea to go so slow during rush hour! I do, however, keep it just below the Misdemeanor level of 80+MPH per NC law.

32 Miles Interstate and 10 miles state highway and about 1 mile other roads:

Date // Inbound / Outbound // SG Avg // Coolant Efan Ran // AC // Outside Temp // CC Used // CC Speed // 485 Avg HI/LO speed

5/17/2016 IN 21.4 YES NO 61 NO 0 LO
5/16/2016 OUT 21.1 YES NO 74 YES 76 HI
5/12/2016 IN 20.8 YES NO 72 YES 75 HI
5/12/2016 OUT 19.9 NO YES 87 YES 77 HI
5/11/2016 IN 21.3 YES NO 71 YES 76 HI
5/11/2016 OUT 20.1 NO YES 82 YES 78 HI
5/10/2016 IN 20.9 NO NO 68 YES 75 HI
5/10/2016 OUT 20 YES YES 83 YES 75 HI
5/9/2016 IN 21.4 NO NO 61 YES 76 HI
5/9/2016 OUT 20.8 YES NO 79 YES 76 HI


This is VERY consistent with what I have seen...and this is with a 2004 Ford F150 4.6/Auto 4x2 Supercab no bed cover with nearly wornout street radials at max sidewall PSI. The extra columns are because I have a dual e-fan setup with one fan set to start at 184F and the second at either 195F or whenever the compressor is on.

I have not done (mostly because it is a PITA) short fills, and I agree...you never know where the pump is shutting off unless you use the same pump each time, at the same angle, etc.

I will update the fuel log to show that my AVERAGE city AND highway is about 17.1 mpg based on the last 5000+ miles, but as a caveat the above is the SGII observations from the daily commutes ONLY...and that is about 80% highway from a cold start. The fuel log shows weekend driving, evening driving with the family (wife and 4 kids) hauling whatever is purchased while out and idling around town.

[redpoint5]

Originally Posted by carolina guy

Our 2006 Grand Caravan has the roof rack with removable crossbars and the only difference I ever saw w/o them was about 1mpg when running empty on my commute (27mpg vs 26mpg)

That still represents a 4% reduction in fuel economy. Not a big deal, but it all adds up.

[freebeard]

Low-hanging fruit. Chop the top already.

[carolina guy]

Originally Posted by redpoint5

That still represents a 4% reduction in fuel economy. Not a big deal, but it all adds up.

Yuppers....they stay in the garage 99% of the time.

[oldtamiyaphile]

Originally Posted by Fat Charlie

I had a 96 Suzuki Esteem sedan that got 40-42 mpg. I didn't log back then, but I calculated at every fillup. I tied a Christmas tree to the roof and drove 2 hours on the interstate, got 20 mpg for the trip.

But did you have it pointy end forward (like the normies) or base end first like the template?

[carolina guy]

Originally Posted by oldtamiyaphile

But did you have it pointy end forward (like the normies) or base end first like the template?

It might have also doubled the weight of the vehicle... ;-)

[Fat Charlie]

Stump first. That may have been a decade before I'd even heard the word hypermiling, but I knew enough about aero to know that if I didn't want all the boughs pointing at the floor when we set it up, it was going stump first. And it was less than a 7' tree, so it didn't quite double the car's weight!