Article: Hypermilling Mitsubishi Mirage

[cyclopathic]

http://www.popularmechanics.com/cars...test-16604530/

In some cases, however, going too slow can hurt your mileage. At the end of our second leg, between Baker, Calif., and Calico Ghost Town, I jumped off the highway and onto the two-lane side road and set the cruise control at a pokey 38 mph. This lowers the engine speed, ostensibly cutting back on fuel consumption, but I didn't see much of a gain on the trip computer. Engine speed is a factor in fuel economy, but so is engine load. At lower speeds, the 1.2-liter inline-three in the Mirage makes more power than it needs. Going a little faster adds more rpm, but the engine load is more balanced with the drag. The sweet spot for the Mirage seems to be closer to 50 mph.

[MetroMPG]

With due respect... he's spouting nonsense.

Slower is more efficient, given top gear and the same terrain.



From:
Thread: Speed vs. mpg/mileage/fuel economy chart - Mirage 1.2L 5-spd and CVT

Also, he misunderstands the difference between "brake specific fuel consuption" and "fuel economy."

He's correct that a loaded-up engine is more efficient (fuel consumed per unit of power produced) than a lightly loaded engine. But the loaded-up engine is still burning more fuel than the lightly loaded "less efficient" one.

He lost the competition for many other reasons than the ones he stated. (And that includes sticking drag-increasing, pseudo-vortex generators on the car's already aero-optimized rear spoiler!)

[cyclopathic]

We need to get OBDII reader hooked up and see what ECU is doing with throttle plate. On Prius Toyota is running ICE at low RPM/low manifold vacuum and throttle plate at ~40%. Would not surprise me if CVT Mirage following similar strategy.

5MT can't do that, but I am really curious what consumption would be in 5th gear at 25-30mph. This should give 1,200-1,500 RPM and enough load to achieve low manifold vacuum.

[MiMi]

I agree that he is spouting nonsense. If I drive at 60 km/hr, my fuel consumption is less than 3.5 l/100 km (67 mpg US). The graph is correct. 1.2 l with CVT.

[MetroMPG]

We need to get OBDII reader hooked up and see what ECU is doing with throttle plate. On Prius Toyota is running ICE at low RPM/low manifold vacuum and throttle plate at ~40%. Would not surprise me if CVT Mirage following similar strategy.

Agreed - that would be interesting to know.

Of course, one reason a hybrid can use more high load/low RPM operation more often is they use the big battery as a buffer for excess power by generating & storing electricity to use later for assist or when the engine is off entirely.

[cyclopathic]

Agreed - that would be interesting to know.

Of course, one reason a hybrid can use more high load/low RPM operation more often is they use the big battery as a buffer for excess power by generating & storing electricity to use later for assist or when the engine is off entirely.

Yeah but not entirely: battery isn't used much at highway speeds.. At steady 60mph it would chum at 1,700RPM due to CVT

EDIT: need to post image, but on last drive got 396mi out of the tank with only 0.5mi traveled on electric (basically in and out gas station). Avg consumption ~50MPG, mostly to lugging engine at low RPM/low manifold vacuum.

[cyclopathic]

He lost the competition for many other reasons than the ones he stated. (And that includes sticking drag-increasing, pseudo-vortex generators on the car's already aero-optimized rear spoiler!)

Could you elaborate? I know that you tested VG on Corolla but found no improvement in MPG.

From what I can see the spoiler on Mirage and rear end overall are designed better than on Prius C, but it is still no Kammback.

On Prius C I had observed MPG dropping from 52-53 to 38-39, by increasing cruise speed from 62 to 73MPH. Reason? Giant bubble behind rear gate. At 45-50mph it would suck fallen leaves and keep them there for many seconds.

Granted the bubble on Mirage would be much smaller, but still.

[Mitz]

http://www.popularmechanics.com/cars...test-16604530/

The Mirage has excellent CD figures. would adding a properly-designed vortex Generator help?

This is an Airtab on a Corvette


mounted on a Race Car


Pictures from:
http://www.airtab.com

[cyclopathic]

The Mirage has excellent CD figures. would adding a properly-designed vortex Generator help?

This is an Airtab on a Corvette


mounted on a Race Car


Pictures from:
http://www.airtab.com

I am sure Metro is well aware of them, read this:
http://ecomodder.com/forum/showthrea...nefits-97.html