CVT 50+ MPG (US) easy sweet spot?

[rjjensen]

so you go 60 and set the cruise in econ mode? am i the only one who doesnt get why this is exceptional...i get over 500 mpg going downhill in neutral...ive averaged over 51 mpg in cruise with the a/c on...just trying to figure out what you are saying...if u accelerate then hit the cruise on and take your foot off the gas the car will decel a bit...your mpg will jump as the car is decelerating...all seems normal to me.

[sleighman]

Come on we are talking 55-60 mph, of course your getting great gas mileage.
At 55 I get an easy 47+ mpg but I almost never drive at that speed.
But at 65-70 mph that drops quickly. 80 mph for get about it. I average 35 which is great considering my heavy foot.

Try driving 60 mph here in Florida on the Interstate and you will cause a crash.

[tacitblue]

I have a theory as to why the "set the cruise setpoint on decel" seems to be a necessary step for max MPG. normally you'll hold steady throttle with the gas peddle and set the cruise, so you are "selecting" the throttle opening to maintain the speed setpoint. with the technique of setting the cruise speed on decel with the throttle closed, that forces the ECU (or whatever does the cruise ctrl management) to open the throttle for you to maintain your speed setpoint. it probably does it just enough to maintain your speed - a more 'minimum' throttle opening than what you would set with your foot... result is best possible MPG ...(?) sound reasonable?

[sleighman]

Originally Posted by tacitblue

I have a theory as to why the "set the cruise setpoint on decel" seems to be a necessary step for max MPG. normally you'll hold steady throttle with the gas peddle and set the cruise, so you are "selecting" the throttle opening to maintain the speed setpoint. with the technique of setting the cruise speed on decel with the throttle closed, that forces the ECU (or whatever does the cruise ctrl management) to open the throttle for you to maintain your speed setpoint. it probably does it just enough to maintain your speed - a more 'minimum' throttle opening than what you would set with your foot... result is best possible MPG ...(?) sound reasonable?

OK, I have to agree this does sound reasonable.

[wizkid057]

I actually had a chance to do this while I had my laptop and ODB2/ELM reader hooked up recently.

It seems that for some reason, when using this technique, the car actually cuts fuel usage (like when you let off the pedal and go into regen braking) when going down some larger hills but doesn't engage the regen braking... causing "infinite" mpg (or undefined, depending on who you ask) while coasting.

This actually surprised me because in the past, and when you're driving normally, there doesn't seem to be a way to get the car to do this. If you let off the gas it cuts fuel but also engages regen braking every time, which drags you slower. The cruise method does it without the drag of regen.

Now, it also seems to do this in cruise at other speeds than 60... but it seems that right around 60 is where it seems to do it the most. Higher (about 65 at most) and theres too much drag to justify a full coast. Too much lower (about 45 seems to be the low end) and you dont have enough inertia for it to be worth it either.

Another interesting point is that this doesn't happen nearly as often if you set the cruise speed while not decelerating... which may confirm the speculation post a couple above this one.

In my CVT version I should also note that during this coast the transmission is still in gear and the engine is still turning, just no fuel being provided.

Pretty cool stuff. I'm glad I stumbled upon it.

[rjjensen]

would you be so kind to explain the technique again...im not understanding it...to me in the video it looks as though you are going downhill slightly...seriously your making small trips and resetting your mileage..if your trip just happens to be downhill you are going to get great mileage.

[wizkid057]

In the video I'm actually going up and down hills almost constantly because of all of the overpasses and such on the highway.

Basically, it seems the only steps that seem to matter are Turn Cruise Main on, Accel to 62 MPH, let off gas, set cruise at 60MPH.

[ShazzNADES]

I got this in a 6MT no cruise control on the way to work. I've got 50+ with cruise control before too.

[gozoner]

Originally Posted by wizkid057

In the video I'm actually going up and down hills almost constantly because of all of the overpasses and such on the highway.

Basically, it seems the only steps that seem to matter are Turn Cruise Main on, Accel to 62 MPH, let off gas, set cruise at 60MPH.

What is your IMA state-of-charge when you start at 60 mph? Does it matter to your mpg readings once you've set the cruise?

[wizkid057]

Originally Posted by gozoner

What is your IMA state-of-charge when you start at 60 mph? Does it matter to your mpg readings once you've set the cruise?

Actually, it makes a world of difference.

I set at 60 MPH regardless of IMA charge, however, I don't see a significant increase in MPG until the IMA is at least 6 or 7 bars charged and there are no green charging bars while cruising. After the green parasitic 1 bar of charging power drops off then the MPG increases much more.