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I got a little present today in the form of my first confirmed 40mpg segment. It doesn't really mean much since it was short, probably downhill, and started on a warm engine. But I'll take it :) This tank is going a bit better than the last. The scangauge is sitting at 32.4 for the tank, with 300 miles driven at just past half a tank of gas. My biggest observation is that constant short trips starting with a cold engine are the biggest impediment to my FE numbers. My morning trip to work could net 28mpg while fighting like mad, but the same trip on a warm engine (which I have tried) could be completed with an average of 35 or 36mpg even if I hit the lights wrong. Granted, this just means that the tank averages are going to skyrocket when the hot weather gets here.

My other biggest impediment is traffic. I've had to start accelerating just a touch faster because of the high likelihood that I'm going to get killed. The road rage factor around here is unbelievable, and it doesn't matter if there is an obvious red light right in front of me. Some people get homicidal when they can't put their foot on the floor. Fortunately that seems to have had no net effect on my numbers.

I never did get to take that road trip last weekend but I should be making up for it this weekend. With any luck I'll be able to put some of this to use improving my highway numbers.

Hi Brick; Great job on your recent segment! For sure, when warm weather comes, you will see a substantial FE increase. I really like the Accord coupe. I have many miles in them. The coupe is more aerodynamic than the sedan, weighs a little less, and looks alot cooler.
Again, nice work! Bill.......

brick do you FAS when your car is warming up? Do you think doing that could have your short trip averages?

I haven't done much in the way of FAS on the short trips. I suppose it's possible that I could squeeze out a few extra MPG that way depending on the route. On a morning like this my engine only just barely gets warm by the time I get to work, so I probably burn fuel 20% faster just because of enrichment and wall wetting. The only problem I have with that is emissions. If the engine is always running cold then the ECU would be enriching the mixture constantly as it fights against me to warm things up. This could potentially mean more unburned hydrocarbons, more NOx, and more other garbage out the tailpipe than if I were to keep it running.

The good news is that this won't be a problem forever. I want to move a bit farther from the city anyway (too much crime where I live), and the bonus will be a longer but very reasonable (15 miles instead of 5) commute with far fewer stoplights.

Hi Brick:

___Something to consider …

___Given you are arriving at work possibly still open loop (that would be a short drive imho?), you may have never lit off the CAT? If it takes the same amount of ICE-On minutes to light off the CAT and bring up the coolant temp etc., you have no emissions other then a small NOx spike on re-ignition from a FAS in many automobiles. You may still be lowering your overall emissions given the high ICE-Off time over that same distance. I am making guesses but I see closed loop ops in 40 degree temps in ~ 2.5 minutes ICE-On in the Accord. With a warm up P&G, it is more like 4 - 5 minutes. FE is ~ doubled and thus overall CO2 emissions are far less given the nice increase in FE over the 5 minutes in either scenario. NOx, PM, CO, and HC’s would probably be higher in the Warm up P&G 5 minute segment however :( 2.5 minutes open loop – 2.5 minutes closed at 25 mpg or 4 minutes open loop – 1 minute closed loop at 50 mpg is the real number to consider …

___Good Luck

___Wayne

Wayne, that is an interesting point. When I first got the scangauge I set it to display open loop/closed loop and to my surprise it was almost always in closed loop, even when relatively cold. This either means that my car is doing something strange or the scangauge isn't reading correctly. I do keep the GPH display active below the MPG display in order to see how rich the car is running. It should be idling at 0.3gph when warmed up, and that takes 1-2 miles of driving to achieve in 30-40F temps. I'll turn the OL/CL display back on this afternoon in case I just missed something.

......that is Gallons per hour (GPH) not gallons per minute. It is a very common measurement in aircraft engines. My Cessna (4 cylinder, 100 hp) burns 4.4 gph during easy cruise, and 7.6 gph on take-off and climb. (air-cooled engines are not very efficient) At 55 mph lean cruise, my 2005 Insight only burns 0.78 gph......................you can see why I'm driving more and flying less.

You're right, good catch. I know what the unit is but screwed up when typing. I think my brain is on lean burn today. Editing...

100 horsepower Cessna?! Whoa, what is it, a 150? What's your cruise speed at 4.4gph? I believe the "book" maximum cruise is 104 kts (around 120mph) but I'm going to guess at 4.4gph you're doing way below 104kts.

Hi Brick:

___All that really matters is that the SG teaches you to drive more efficiently. I can see the payback in less then 3 months at the rate your segments are improving ;)

___Bill, are you using the “Climb and Glide” technique in the Cessna yet? 7.6 gph on the climb and 0 gph on the glide … What do you think, 4:1 Glide to Climb distance ratio with a 1.9 gph consumption rate at an average air speed of maybe 60 mph? Hmmm … 60 mi/hour / 1.9 gallons/hour = 31.5 mpg ;)

___Good Luck

___Wayne