What's the best MPG you've ever managed?

[SoulAssassin]

71.5MPG in a Jeep Wrangler

http://picasaweb.google.com/ge...to#5132631530147343362

 

[thomsbrain]

Originally posted by: JEDI

Originally posted by: thomsbrain
Yesterday I averaged 57.8 MPG in my 240 HP Accord over 29 miles at ~55 MPH. Downhill, of course.

But the trip uphill over the same route was 25.1 MPG, giving me an average of 41.95 MPG round-trip.

That figure was verified by my GPS and pump calibrated ScanGauge II. That's my best round-trip score since getting the gauge. It's also a great example of how engine efficiency increases with wider throttle openings. I used the mountain as a "momentum battery," ran the engine harder filling up my "battery," then cashed in the momentum downhill, where the engine used automatic fuel cutoff to coast a lot of the way back down using no gas. The result was less gas burned than if I had simply driven the same speed at constant throttle over level ground.

I've found that with a careful right foot, I can average ~35 MPG over long distances, including up and down mountain ranges.

momentum battery?????

so you gun the gas going up hill and use little/no gas going down hill.

and that uses less fuel than constant cruise control???

that doesnt seem possible. gunning the engine = higher RPM. the higher the rpm, the less effieicnt fuel econ is.

You are right that high RPM would be bad, but I didn't have high RPM. Gunning the engine only changes the RPM if you shift or accelerate. I did neither, saving all that extra energy in altitude instead of velocity. I guess "altitude battery" makes more sense than "momentum battery," which is misleading. The V6 in the Accord makes enough power down low that there was no need for even a downshift out of 5th gear despite adding roughly 4000 feet worth of elevation. Most of it was well below 2000 RPM. Since engines are more efficient at wider throttle openings combined with low RPM, and since I didn't use any gas at all for most of the way down, it wasn't a surprise to see my total mileage come out significantly higher than I can achieve driving the same speed on level ground (which is closer to 35 MPG).

This is no different in concept than the Chevy Volt, which uses a tiny gas generator running at wide throttle for a short amount of time and stores all the energy in its battery, achieving net mileage that is extremely high because the engine either runs full blast or not at all, and the battery and electric motor serve as buffers that allow that to happen. The mountain was my buffer.

This is also the same concept as "pulse and glide," except that I did one super-long pulse, followed by one super-long glide. In pulse and glide, the extra energy gets stored in your car's momentum when you run the engine hard, then you shut off the fuel and coast. I stored my extra energy in altitude.

If it doesn't make sense, just remind yourself that 42 MPG from a V6 Accord over roughly 60 miles round-trip just doesn't happen unless there's something special going on.

 

[fleabag]

Originally posted by: JEDI

Originally posted by: thomsbrain
Yesterday I averaged 57.8 MPG in my 240 HP Accord over 29 miles at ~55 MPH. Downhill, of course.

But the trip uphill over the same route was 25.1 MPG, giving me an average of 41.95 MPG round-trip.

That figure was verified by my GPS and pump calibrated ScanGauge II. That's my best round-trip score since getting the gauge. It's also a great example of how engine efficiency increases with wider throttle openings. I used the mountain as a "momentum battery," ran the engine harder filling up my "battery," then cashed in the momentum downhill, where the engine used automatic fuel cutoff to coast a lot of the way back down using no gas. The result was less gas burned than if I had simply driven the same speed at constant throttle over level ground.

I've found that with a careful right foot, I can average ~35 MPG over long distances, including up and down mountain ranges.

momentum battery?????

so you gun the gas going up hill and use little/no gas going down hill.

and that uses less fuel than constant cruise control???

that doesnt seem possible. gunning the engine = higher RPM. the higher the rpm, the less effieicnt fuel econ is.

The idea is that he achieves peak/near peak torque during high load situations and therefore most efficient use of power/fuel. Utilizing peak torque during highway driving doesn't yield better mileage in most circumstances because the load on the engine is far lower than when you're going up a hill. Peak torque is when the engine is running most efficiently but not the least amount of fuel. It also depends on how quickly you reach peak torque because you could reach 200ft-lbs of torque at 2500rpm, 250ft-lbs at 3000rpm and then reach peak torque of 260ft-lbs of torque at 3600rpm, so gunning it at 3000rpm would probably the best usage of fuel while giving him the most power which he would need when going up hill. It also depends on how long the hill is; if the hill is steep and short, then speeding up before the hill and using momentum to get over the hill, then losing speed would be a good usage of gas opposed to maintaining speed, downshifting and continuing with the same speed.

This is all speculative as we don't know a lot of factors regarding his vehicle. What we do know is that the load changes when you go up a hill and so does the throttle, maintaining speed wouldn't necessarily be the best way to achieve good mileage for his particular vehicle.

 

[canadageek]

about 5.5-6.0 L/100 KM in a merc C-class. average speed of 150km/h or so

 

[CyberDuck]

Got my new Skoda Octavia 4x4 TDI one week ago. According to trip computer the average has been 6.6 litre/100km (35,6 miles/gallon) for the first week driving 80% short town trips, 20% small twisty roads.