I work on a navy base where the speed limit is 15 to 35 miles per hour (strictly enforced). That's the last 1.3 miles of my commute. The 3 miles before that is 35 - 45 miles per hour. I used to try and get the car to run in EV mode as much as possible during that time by doing about 40 in the 45 zone when no one was in back of me. Problem is that the the battery level would drop too low during the last part of the trip and I was running on the ICE doing 15 miles per hour on base.

At 45 - 55 miles per hour while running on the ICE I'm getting over 30 mpg. At 15 - 25 miles per hour I'm getting 15 - 20 mpg. I found that I was better off running in EV mode in the 35 miles per hour zones and putting the speed to 53 miles per hour in the 45 zone. That keeps me below the ticket threshold, the car runs more efficiently at 53 than 45 and when I arrive on the base I have a full charge on the battery.

Moral of the story. Save the battery for when you'll get the most benefit.

I have experienced that same effect just today. Was traveling in areas that had 20-30 miles per hour speed zones and I used the E mode 75% of the travel time until finally the battery got to low and my analog mpg gauge was stuck at 10-20 mpg for some time there after. Total trip mpg was well below 30 mpg, so I agree with your theory.

Orcrone - is your commute level or varied terrain?

I live in southeastern Virginia. If it weren't for overpasses we wouldn't know what a hill is.

Great advice Marc. I often get in stop/slow and go traffic during rush hour going home on the freeway. I've found by watching the battery SOC display I can get the most out of my EV capacity. I use the ICE when I accelerate if the SO is under 2/3 to keep from draining the battery to the point the ICE runs to recharge the battery, even if I'm stopped.

The SOC lets me decide when to back off the throttle and use EV or move along slowly with the ICE to restore the SOC a bit. It really does help.

Ah, it's "fun with numbers day"...

Your less preferred method of maximizing EV on the 3 mile leg yields:
3 mile portion: 0 gals
1.3 miles at, say 17.5mpg: .074286 gals

Your new preferred way:
3 mile portion at 40mpg: .075 gals
1.3 mile portion: 0 gals

You said you'd get over 30mpg using ICE on the 3 mile leg, but in order to actually break even you'd need to get at least 40mpg on this leg.

Looks like a close call... Who cares whose behind you, we need exact numbers!

Two climate control systems, one inside and the other at the tailpipe.

2007 Camry Hybrid (in service June 2006)
FE: 6.77L/100km (34.8 mpg) over 37750km (23450mi)
75% city - Ave trip 20 min - 2 Winters

With the non-preferred method the ICE will turn on occassionally. When I first get on that road I accelerate using the ICE and when the speed goes from 35 to 45 the same will happen. Plus there's turns in the road causing me to accelerate and decelerate. So keeping it in EV mode the whole time is pretty difficult.

In the preferred method the ICE turns off when I turn onto the base's road, so the entire 1.3 miles is done with the ICE off. In addition, about 1/2 mile to a mile of the three miles leading up to it is in EV mode. It's only the 45 miles per hour zone and while accelerating that I'm using the ICE. The last part of the 3 mile leg is at 45 miles per hour, giving the battery time to charge before reaching the base.

So it seems that the preferred method is yielding better fuel efficiency. There's also the psychological angle to FE (boy, this is getting weird). I don't mind seeing the ICE turn on when going 45 miles per hour. However, when I'm on base the limit will go from 15 to 25 miles per hour. The ICE will turn on when I accelerate. But then when I ease off the accelerator the ICE stays on even if I let off the pedal, even though the display shows the SOC at 50%. And I'm sitting there going "**** you HSD, I only have 3/4 mile to go. Shut off that engine ". I've even thought of bringing a small animal with me to make my sacrifice to the FE gods. (Just kidding, please don't sick PETA on me.)

Can't do that. Until the TCH I was the one in back of someone going slow calling them every name in the book.