I was watching my DW driving my FEH and noticed she was using a variation on p&g. She accellerates to her speed but instead of coasting she gives just enough gas to not quite maintain speed. I was thinking about this and with my SGII hooked up I would accereate agressively to use HV battery with heavy electric assist using fake shifts to my desired speed then try to hold just above 40 mpg on the mpg display this seems to have paid off well esp on the highway. What do you guys think?

 

Yes. I think many people just do that instictively. I know I do.

Also, when I'm doing true P&G in the city ( under 40 MPH ) I don't beat around the bush like GaryG at 1800 RPM. I acceralte quickly, 2400 to 3400 RPM which gets me to 40 MPH much sooner, and then my FEH is in EV for a greater number of minutes per hour, which pays off big time.

I get 54 MPG or higher in the city most of the time in above freezing weather.

On the highway, in a 2005, cruise control really lowers your MPG.
At any speed, and on the flattest parts of Kansas and Nebraska, I always get better MPG, by 4 or 5 MPG driving manually. DWL is best for highway, IMHO.

 

There are so many factors like headwinds, tailwinds and highway speeds, etc. that determines a strategy for me. Sometimes a quick burst with electrical assist to make a stoplight yields me more MPG than stopping and grabbing some regen for the take-off again. The trick for me is don't let that RPM stay high long as the assist will take me.

By watching engine Load on the SG, you will notice you have to be at 99% load to get assist after warm-up. This means two things - your engine is at WOT (putting the most air/fuel mixture through the engine), and also using energy from the pack that has to be replaced at highway speeds.

Headwinds generally put coasting in "N" at a stop for me because trying to get back to highway speeds cost to much MPG. What I do is reach the desired speed and back off the accelerator to maintain speed at the lowest RPM. On flat roads, Speed Control works great for doing this also.

Tailwinds allow me to use coasting in "N", but I find accelerating as slow as possible back to speed (no assist) is better for MPG for me. At highway speeds with a full SoC, I find that letting MG1 maintain the SoC allows the ICE a chance to get out of the negative split mode during charging. During negative split mode, the generator is using braking energy to decrease engine speed. Neutral coasting also eliminates the negative split mode when the HV battery is full.

GaryG

 

I have the nav system and when I have it in power flow I have noticed the amount of ICE power flowing to the drive wheels is less by half than the battery power flowing to the wheels when I do a short hard accell (3/4 throttle) up to but not over 4k approx 1 second long. It will dump 2% of the soc and get me about 15 mph. I usually do this with at least a half or better soc. If I drop the soc to low ie 46% I spend to much ICE mpg recharging. I find I loose less average mpg than a slow accell up to speed (60-65 mph)

 

Mark, are you saying instant MPG seems better, or are you saying your current trip average is better? I've posted the torque curve many time here and 3,000 - 3,500rpm's is almost flat in the FEH/MMH. As far as speed control, I got better than John's 48mpg at 48mph with my speed control vs manual with 51.4mpg average on flat roads. Wayne Gerdes ask me to do the test for his presentation at Hybridfest over a year ago. See the steady state speed chart at: http://www.cleanmpg.com/forums/artic...brid--350.html

If we are talking about city driving where I accelerate at 1800-2400rpm's, there is a calculated reason. The slow acceleration allows Fake Shifts and MG1 time to build SoC to go EV longer. The low rpm's save fuel. I've proven my method works at Hybridridfest, but I don't see how John's techniques would ever work myself. When I accelerate like John claims, my MPG takes a dive every time.

IMO, there is no magic thing that works for all conditions. I take every condition differently.

GaryG

 

My average mileage is better. I drive 70% on the highway and I have to enter without the aid of an on ramp. I turn right onto a highway with a speed limit of 70 mph. What I have found is if I use the slow to moderate accell up to my speed my average will drop .3 mpg on average. If I use the more agressive accel which uses more hv battery (almost pegs the discharge gauge) and less fuel. Now this is definately a fake shift style accelleration. I will accell till i see the gauge start to fall back then I lift off the throttle and back down on the throttle untill I reach my speed.

 

What this thread shows is, there is no single correct way of doing things.

Gary's methods work for him.
My methods work great for me.

I will say, that from 2 years of discussions, I am probably getting better MPG than Gary with higher speeds, and he probably gets better MPG than me at the slower speeds, which is great. We are both doing what works well for us. I do most of my miles at highway speeds at or over 65 MPH and have an average of 37.7 MPG in all seasons mixed. When I do my 25% city condition driving, I'm always in the 45-54 MPG range.

Again, this car is so well designed, your exact technique looks less and less important as we go along. -John

 

I disagree John, Wayne Gerdes refers to hypermilers having a bag of tricks. I agree with Wayne, but I call them techniques. No matter the speed, I find the techniques that work for that situation. Everything is basic knowledge, and I adjust my techniques to handle the task.

The torque curve, and your acceleration recommendations don't add up. Sorry, nothing adds up with your mileage to me with your stated techniques.

Mark, accelerating on a highway is not a P&G event. I pay that price all the time.

GaryG

 

Thats why I'm bouncing it off you guys.

I got off topic in the original discussion.

I'm just trying different things, thinking about conservation of energy etc. (aircraft term)
When I was flying the goal for good fuel burn was to get to altitude as quick as possible, Altitude was energy. Altitude was where you got your best fuel burn. the longer you stayed at a lower altitude the more fuel you burned. Once at altitude you could throttle back and make a VERY shallow decent and really save fuel, but you traded altitude. If you substitute speed for altitude this is what I am trying.

 

Well, maybe what they say is true then? Maybe you can't teach an old dog new tricks.