Extreme hypermiling attempts

Hi all
I just want to open this new thread to post some "hardcore" P&G tests I made so far with my 2010 Prius. New posts and suggestions are welcome.

When I say "extreme" in the thread title I mean that I try to find out the best road conditions (no cars and no traffic lights), the best P&G and the best car setting to maximize fuel economy.
During these tests I had to consider:

• no gradient paths in favor (ex: start the test at 10m, end at 10m high).
• overall consumption of traction battery = 0 (ex: beginning SOC=55%, ending SOC=55%, SGII is very useful here).
• commutes should be far enough to find out a reliable average (I would say at least 20 km that is around 12 miles).
• Beginning and ending speed must be the same (starting from 0 km/h, ending at 0 km/h for example).

The first test I made was at the end of march 2011, one month ago. the P&G I used was the following: accelerate from 35 to 57 km/h (22 to 35 mph) with ICE running at 1360 rpm or so. In this way I could complete almost every P&G cycle with energy balance "from" and "towards" battery = 0.
I tried to keep the SOC at 58%.
The result is shown here:

TripB: 62.3 km (38.5 miles) - Cons. 2.6 l/100km (90.5 mpg) - AVG 40 km/h (25 mph).
Outside air temperature was 8°C (46°F). To keep ICE coolant between 85-87°C (185-190°F) I had to use lower grill blocking, covering about 50% of the surface.

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Since I have a target of 2.0 l/100km (117.6 mpg), this early morning coming back from a club, I tried some more tests, hoping that warmer temps could help me to do a better job.
I made 3 different P&G tests:

1. P&G from 35 to 50 km/h (22 to 31 mph) and SOC = 60%
   
   TripB: 18.1 km (11.3 miles) - Cons. 2.3 l/100km (102.3 mpg) - AVG 37 km/h (23 mph).
2. P&G from 35 to 50 km/h (22 to 31 mph) and SOC = 45%
   
   TripB: 17.6 km (10.9 miles) - Cons. 2.4 l/100km (98 mpg) - AVG 38 km/h (24 mph).
3. P&G from 35 to 68 km/h (22 to 42 mph) and SOC = 55%
   
   TripB: 21.6 km (13.4 miles) - Cons. 2.5 l/100km (94.1 mpg) - AVG 46 km/h (28.6 mph).

In all tests I used to pulse at 1800 - 2000 rpm, to keep ICE at the most efficient speed: I guess you all know the 2ZR-FXE chart that Ken1984 showed us:

where is clear that the most efficient 220 g/kWh area is between 1250 to 3000 rpm: Thanks again Ken.
For these tests: 15°C (59°F) outside temp - with no wind - on the same flat roads - starting and ending at the same place, with the same speed and with the same SOC.
In the second test where SOC = 45% I noticed that during the pulse phase more ICE energy went to the battery. I think that this was the reason why I had a worse fuel economy result than the first one.
The car has more or less 19500 miles and has a solar roof.
Tires (Bridgestone Eco Pia B250 195/65 15) were inflated 2.9 bar (42 psi) front and 2.8 bar (40.6 psi) rear.

I know that someone got 2.0 l/100km (=50 km/l =118 mpg), so now I'm wondering what there's to improve on the things written above to reach such a great result.
- Maybe a warmer outside temp can help? With no grill blocking ICE coolant was at 80°C (176°F) with 15°C outside, perhaps a 88-90°C coolant temp would give a better ICE efficiency.
- Maybe a different P&G speed range?
Suggestions are welcome.
Bye
PS: I wanted to share my driving experiences with you, but I apologize for my english, I know it's not good: I didn't have the chance to practice a lot.

 

Tires (Bridgestone Eco Pia B250 195/65 15) were inflated 2.9 bar (42 psi) front and 2.8 bar (40.6 psi) rear.
Running in ECO mode all the time, without using A/C , fan off.

 

Thanks Giora. About the HSI, I took a picture of it and I draw the zones where I was working, just to explain better. Here it is:

About the pulse zone ICE was running around 1800-2000 rpm. In this phase some energy went to the traction battery (I see negative amps in my SGII, and a higher SOC at the end of the pulse).
Typical SOC values before and after pulse were: 60.0% --->60.5%.
About the glide zone, you see that is a very tight space. That's because every energy conversion has a efficiency less to 1, so there's always some waste of energy. I just glided to use the 0.5% SOC that I gained during pulse phase.

Thanks SageBrush, I think the same: warm weather should help. But I doubt it will be enough to get the 2 l/100km I am aiming.
Yes, it was 3 am, I was coming back from a club. Actually that's the only time when traffic allows this kind of games.

 

Oh, yes, thanks, just corrected.

Ok, thanks for the advice, I'll do my best next time.
But it will be hard for me to find a road that allows these tests during the daylight.