This is mostly just a fun question to satisfy my curiosity.

I have a 99 Disco 2. Around town I get 14 MPG. On the highway I get 15 MPG on flat terrain going about 70 MPH. I just made a round trip from Sacramento to Reno and back today. Sacramento has an elevation of about 100 feet. I had to go over the Donner Summit at an elevation of 7000 feet, then descend to Reno at 4500 feet. I drove 268 miles round trip without stopping for gas averaging about 65 MPH. My route home was the reverse of my route to Reno. I filled the tank when I got home, and determined that I got 18.1 MPG! I have noticed this before, that I get better mileage when traveling over the Sierras.

My engineer's mind can't explain this. For every bit I went down hill, I also went up hill the same stretch of road. I can only really think of two things which could contribute to this:

1) Going downhill helps mileage more than going uphill hurts it. I'm not sure that this makes any sense. It certainly doesn't from a physics (conservation of energy) point of veiw.

2) I get significantly better mileage at higher elevation. Does anyone have any experience with this? Maybe I should move to Tahoe to improve my mileage! With what I save on gas I could buy a pretty nice house (ha ha.)

I guess it is possible that my Disco has a secret anti-gravity option that only functions when going uphill, but I kind of doubt it.

Anyone have any thoughts?

Elliot

 

I would think that reformulated gas is the difference.

 

No, I filled in Sacramento before I left, and only refilled once I made it back home to Sacramento.

 

I have noticed 18 mpg when using BP/Amoco 93...even though there are other 93's The Chevron/BPAmoco get 18....I really am confused...I guess there are certain formulas that work better...most of my driving is HWY. some city
That is odd though.

 

actually this does make sense in the context of diminishing returns. my thoughts:

1) lets say you use (x) gas while traveling on level ground. when you encounter a slope (y) you will use more gas (say x*1.1) to travel up that slope. if that slope value (y) increases linearly (2y), then your fuel comnsumption increases, but, thanks to the inherent inefficiency of the internal combustion engine, you will need to increase you fuel rate more than an additional '.1' increase. essentually your linear increase of slope increases your fuel at greater than linear rates. of course, theis is waaaay oversimplification of the concept.

2) also, rover transmissions dont seem particulary suited to highway mountain driving very well (im in colorado), and constantly downshift to maintain speed. a lower gearing at speed will also significantly contribute to worse fuel economy.

3) on the way down the hill you are essentially idling in gear most of the time. whether you are coasting down a 2° slope or 5°, your lack of fuel usage is the same, keeping you fuel usage closer to a low linear value.

just some thoughts

 

it is a matter of air temp. and barametric pressure. cooler temp, less pressure, get better fuel burn. thus better mileage. getting a good match on the air flow in and out of the engine will also help. I average 22 mpg on hwy. and 18 in the city. I usually drive about 5mph under the speed limit. hope it helps. if you want more specific information on the changes let me know. i beleive all rover are capable of similar stats. hope it helps, gotta love a rover. duboff