99.9+ Trips

Do you mean like this, 80.1 miles at 99.9 MPG?


Average descent was about 65 feet per mile, but much of that was concentrated (and wasted) at the start of the segment. A more consistent slope should have been able to achieve the same result with a drop of only 25 feet per mile.

There are people who do better with no downslope at all, but I'm not (yet) at that skill and patience level.

 

No way I'm beating you guys but here is mine. The elevation drop was 50ft. Per mile.

 

I think you are only slightly elevation impaired. Since you have already done this, either a 4% improvement to your P&G style or an additional thousand feet of altitude could produce a trip that clobbers my distance.

 

If I did a pulse & glide session minus the long trip from work to the P&G location I could stay over 100mpg but who has that kind of time. I think.

 

I've only had a +99.9 mpg trip once register on the ScangaugeII ( +135 mpg over 10 miles) going to work from the dealership. My guess is that the most significant factors was a prewarmed up gasoline engine, a top speed of less than 35 mph, a trip/route that minimizes the need to brake.

 

We can approximate the descent/mile required to turn a 75 mpg trip on level terrain into a 100 mpg trip:

~ 12,400 wh a gallon at the wheels,
so 12,400 / 75 mpg = 165 wh/mile
100 mpg = 124 wh/mile

So descent requires 40 wh a mile of potential energy (PE) = 144,000 joules
PE = mgh , so 15000h= 144,000, and h = 9.6 meters a mile.

For some reason Fuzzy and I come up with similar numbers in these games

 

I like it better at 99.9 so Fuzzy doesn't look so much cooler than me. Now I'm going to have to make a trip to Reno and back so I can try and do better. lol

 

is there a way to normalize the score? from oo.00 to 1.00?

 

Normalized score would be from 0 to 1 = it's a mathematical technique when you want to express a variable as having two sides - in this case I was thinking of a score that said that said this was easy or that was hard to do. With respect to gravity there straight up (1.0 =very hard unless your in a rocket) or straight down (0.0= very easy until you hit the ground). However, a Prius going downhill or uphill would be somewhere inbetween. ooh never mind.

 

Mark, normalization means to even out the effect of a specific variable between results. You can think of it as eliminating that variable'e influence as the reason for different results.

Specific to this thread, Walter may have been asking if you are trying to come up with an equation that figures out trip MPG had no descent been available. That was why I posted earlier the descent breakpoint for greater than a calculated 75 mpg flat trip.

Anyway, if this is you intent then I think the easiest approach is to just consider the trip as two parts:
(1) Potential energy/mile (as a function of average descent/mile;
(2) Energy/mile at the driveshaft during the trip
The normalized (for descent) value is (1) + (2), which gives the energy/mile if the descent was leveled.

Then it is just a matter of arithmetic and flipping units around to get back to the always annoying MPG unit

 

To be honest I'm not sure why posting 99.9 mpg runs from downhill trips is attractive, but perhaps I misread your intent ?

 

For one, I see it is a response to the VW TDI Tank Wars web site, which required only a 15 mile minimum distance and had no restrictions on elevation change.

For another, the longer the distance, the less useful the downhill boost. This thread just acknowledges reality by requiring an elevation disclosure. Many newbies are unaware of the major impact of elevation.

Finally, the eventual 'winners' will have comparatively little or no downhill boost. Uncle Wayne & many of his students have pegged their displays at 99.9+ on closed circuits (no downhill assist). The record setting Japanese commuters have beaten 100 MPG for full tanks, one of them in excess of 3000 kilometers. At that distance, elevation change is hardly relevant.

 

I have been told that I have this wild imagination but I was thinking of two particular scenario:

(1) A Prius drives a straight route going 70 miles at and average of 35 mph on a completely flat smooth asphalt road where the beginning elevation and the ending elevation is 500 feet above sea level. There is no traffic ( the Prius is travelling in non-rush hour), traffic lights, stop signs, or toll so the Prius doesn't have to stop and this is one continuous trip. The Prius driver is mainly using Pulse and Glide hypermiling technique where his top speed is 50 mph and his bottom speed is 30 mph but his median/average speed is closer to about 35 mph.

(2) A Prius drives a straight route going 70 miles at and average of 35 mph where the beginning elevation and the ending elevation is 500 feet above sea level. However, as the Prius travels along this straight smooth asphalt road the elevation of the road rises up to an elevation of 900 feet above sea level for 2 miles and then drops down to an elevation of 100 feet above sea level for the next 8 miles for every 10 miles until the last ten miles. On the last ten miles of this hypothetical 70 mile route , the road rises up to an elevation of 900 feet above sea level for 2 miles and then drops to an elevation of 500 feet above sea level for the next 8 miles. There is no traffic ( the Prius is travelling in non-rush hour), traffic lights, stop signs, or toll so the Prius doesn't have to stop and this is one continuous trip. The Prius driver is mainly using Driving with Load hypermiling technique where his top speed is 50 mph and his bottom speed is 30 mph but his median/average speed is closer to about 35 mph.

Is a comparison of the energy efficiency results fair? Are the challenges of the two scenarios comparable? Would it be useful to have a fuel efficiency scoring mechanism that reflect the potential difference between the road conditions and driving technique used? Given a topolographical elevation chart of road/trip/route from let us say Google Earth that we could somehow give it potential *score* and would this potential *score* be the same for both scenarios?