Ever since getting the FEH and starting hypermiling, I've been afraid of hills. Mileage drops precipitously when climbing hills and I've avoided them when I can. However, we just got back from a trip over the hill on highway 17 to Santa Cruz. It's a gorgeous drive. I decided to reset my mileage in Los Gatos, at the bottom of the hill, and see how bad it would get. I kept to the speed limit, which is 50 in some places and 55 in others, and even 65 going through Scotts Valley near Santa Cruz. Mileage on the way up was "bad", around 26, which is actually better than I expected. But cruising downhill on the other side got my battery fully charged AND brought the mileage up over 40 (!). I got almost the same numbers going the other direction, back home. It seems running uphill is a good load on the engine, and it is running very efficiently. At 50-55mph on a flat, I would have expected 40-44mpg. Getting 40 going over the hill was a pleasant surprise. I won't be afraid of hills any more.

RayP

 

I've had the same good experience with hilly loop routes and increased mpg. Someone here, either gpsman1 or garyg, had an explanation for this phenomena that made sense but I don't remember it now.

 

It was GPSMan1 who first documented how to handle the hills. You might be able to obtain even better mileage than what you reported in this thread if you obtain "fuel cut" on the downhills at speeds over 40 mph.

I'm assuming you did not obtain fuel cut on your downhill drive because you did not report such an event. If I am wrong, then I need to correct myself.

 

Hi Don

After the '07 Hybridfest MPG Challenge driving in rolling hills for the first time, I determined hills were better than flat Florida roads for MPG. It's like the opposite of running uphill to train your lungs and leg muscles for a marathon. Instead, learning how to get the most out of a glide or coast on flat roads prepare you to really take advantage of gliding in the hills. It's like a roller coaster effect where you gain speed on the downhills to help sling you up the uphills. Those long hill climbs is where the Driving With Load (DWL) technique comes into play. This is where you hit to hill at or slightly above the speed limit and determine the minimum speed traffic will accept behind you. The goal of DWL for me is to slowly decrease speed as you climb to the top of the peak. Never get caught falling below a acceptable speed in traffic climbing the hill where you must accelerate to increase your speed going up the hill. For my '09 FEH I've learned my pulse (acceleration) used in my P&G technique is the best way to maintain that minimum acceptable traffic speed. I use my SGII Instant MPG gauge to determine my pulse rate which is ~15mpg on the '09 2.5L engine. This pulse rate prevents electric motor Assist and allows MG1 to continue to charge the HV battery.

I grew up in Santa Clara and went to the Santa Cruz Boardwalk many times when I was younger back in the 60's and 70's. Never drove an FEH there but rolling highways give you better options for MPG than my present flat highways here in Florida. I use fuel-cut at highway speeds here in my P&G technique as one options depending on traffic. If I were Ray, I would consider a 15mpg Instant reading for the maximum pluse while climbing hills and try not to get to a slower speed to require use of electric motor assist. I also use EV climbings but set a minimum SoC percentage of 42.5% so I can still go EV at the top of the hill or bridge in my case. As a new rule I try not to ever go below 42.5% SoC or a point I can't go EV anytime.

GaryG

 

I am assuming fuel cut is the shut-off of fuel to the injectors at zero throttle, correct? If so then I took full advantage on the downhills. You can see the FE rise rapidly in this situation, more so than if you give even the slightest throttle. Much of the way downhill I was also slightly on the brakes to keep at the speed limit, and the result was a full charge at the bottom. So full that I started noticing significant EV boost at 50-55mph even with moderate acceleration. A scangauge would be helpful (I don't have one) to check the SOC but you can infer a lot from the observed operation.

RayP

 

Very good Ray!

Hope you've read what Rick and I found with DFSO and a SoC lower than 46% posted in the '09 techniques thread on Cleanmpg.com. We both needed the SGII to find out how and when DFSO works in the '09 FEH. This is pasted from that thread:

"I started thinking about this 46% SoC requirement and why the brake tap changes that requirement. When we tap the brake pedal it's signaling higher regen so the battery below a 46% SoC can allow MG1 to stop charging and provide an engine idle during DFSO. Tapping the brake could allow MG2 to start supplying A/C power to MG1 to hold the idle directly without conversion losses going through the battery. At or above a 46% SoC the TBCM reduces the demand for a fast charge so MG2 can provide enough current during decel to both MG1 to hold the idle with excess going to battery charging. The Pcm is what controls DFSO so the tap sends the message from the brake pedal switch for additional regen. Once that message is sent by the tap the Pcm takes control of regen and DFSO and does not reverse its command.

I think the same thing is happening with the accelerator blip. The command is sent from the pedal to the Pcm for a restart from EV , but we fooled the Pcm for a split second and don't get the rest of the command to use the electric motors to do the NVH thing and burn that additional SoC.

I'm glad you are using the accelerator blip with some success and you agree it can work. It does not sound like many are posting about their success with it like I am. I would say 98% of every blip restart from EV works for me now from a stop all the way up to 40mph in EV . Sometimes I lose up to .3% SoC but that is much better than allowing the Pcm to drop the SoC down to 38.8% (1.2% loss from a 40% automatic restart). If I save 1% SoC 100 times during the day and you get 12% SoC (40 - 52% SoC) out of a full battery, that's 8.3 full charges using no regen or gas. Lets say on average I get 1.3 miles out of every fully charged battery without P&G in EV . That's 1.3 miles X 8.3 charges = 10.79 miles free that those people not using the blip can be paying for in city driving. Now 100 blips for restarts sounds like a bit much, but I run P&G with between 40.4 and 42% SoC on average in city driving. The reason is because a low battery SoC charges faster and I can go back to EV much faster. As you can see the blip really makes a difference for me."

Ray, if you want to really get into hypermiling or just better understand your '09 FEH, I recommend getting a SGII. CarlD discovered the accelerator blip with his SGII SoC gauge. My Son just gave me a second SGII for Xmas which is the new 3.17 version. I'll post any improvements or problems when I get it installed and programmed. I got my first SGI in 2005 and gave that to a friend and now I have 4 SGII's to monitor my '05 FEH and '09 FEH. I may use 3 of them in my '09 just to see how that works out then move 1 more to my '05 FEH. I need to order another 6" ethernet cable to daisy chain the SGII's all together.

GaryG

 

a) I just drove from Barstow to Anaheim CA which is more than 60 miles IIRC and utilized fuel cut in my 2005 frequently on downhills incl. most of Cajon and net 82.4 mpg. In fact, I went from Vegas to Anaheim on 7.5 gallons doing the speed limit... mostly. Met heavy traffic last 20 miles and averaged 15 mph with lots of EV time. The 2005 mostly needs to be in L to get fuel cut but 3x I had it occur in D.
b) I could not get 3 SG to work at once in my 2005... not enough power or signal.

 

Yup, hills rock! At least unless you live on top of a big one, drive downhill to work on a cold engine, and then drive uphill home on a cold engine...then they suck!