If it's already been discussed, I missed the post.

I was thinking, since we hybridians consider every angle from tire overinflation to pulse and glide techniques to eek out more mpg, is anyone in the practice of only partially filling his or her tank in order to save weight and therefore increase mpg. If so, what have been the results?

As has been frequently discussed, a lack of momentum or starting from a stopped position is a significant factor we battle in fuel consumption. We know that one can pretty easily drive ~200 miles on 1/3 tank...that same 1/3 tank weighs 100lbs less than a full tank of fuel and although we could hypothesize that 100lbs wouldn't matter much, we don't know what effect 100 extra pounds might have on our fuel consumption unless it's been tested. Has anyone tried this? Anyone want to try it?


I thought I'd get the community to 'weigh' in on this 'heavy' issue.
Pardon the puns.

 

I'm sure moving less weight around will save some fuel. However, when you figure that the car, passengers and fuel weigh over 4000 pounds, 100 pounds is not a large difference. One of the joys of driving a hybrid is going 600+ miles between fill-ups. I'd hate to go 200 miles just to put five gallons in the tank every four or five days.

Also, I think that the savings would be small enough that any difference in mileage would be difficult to measure due to the normal differences in mileage experienced.

 

you would increase mileage by 1-2% by reducing your car's excess weight by 100 pounds.

http://www.ftc.gov/bcp/conline/pubs/autos/gasave.htm

There is a benefit, but I guess it will depend on whether you'll find the more frequent fuelings worth the benefit.

 

I suppose you could also ask your family members to diet. Or get a smaller family!
Seriously, I would't fill up twice as frequently for even a 5% improvement. I'm thrilled by my 500-600 miles per tank.

 

I do try to leave my wife at home. Less weight in the car and no nagging about the milage. Doesn't help much.

Also since I calculate my milage by actuals (not "indicated") I'd never be able to know what my "real" mpg savings would be until I eventually filled up.

 

I could swear that i get better FE without my wife riding in the car. She is 150 lbs.

 

You just told everyone how much your wife weighs? You'd better hope she doesn't read this forum.

 

6lbs per gallon*10 gallons is only 60lbs. Not worth the effort alone. Unless you are going for every bit of mpg per gallon. 60lbs is only worth about .25mpg or so at 50mpg.

 

She doesn't

 

Well at a third full vs half a tank I was figuring 6 gallons in the tank and filler neck vs about 18.

My calculations were also based on 8 lbs/gallon of gasoline, which could be off, but I thought gas weighed closer to 8 lbs as opposed to 6. I've seen quotes of anywhere from 6.62lbs to 8, and being a salesman by nature, I figured I'd use whatever number best represented my case.


I still submit that I have always found my vehicles a bit more sluggish after filling the tank, and even though the increase is marginal, adding 10 more pounds of pressure in a tire vs @ manufacturer recommended pressure I doubt would give much more than a 2% increase in FE.

Anyway, glad I started this thread...we all now know how much FL07's wife weighs, and if he gets kicked out of the house...he can crash at my pad!