Bad commute mileage

<div class='quotetop'>QUOTE(meezercat @ Jul 27 2006, 08:48 PM) [snapback]293568[/snapback]</div>

Yep, I bet your consumption screen showed lots of 5 minute segments with little to no mpg, eh? One example of sitting still. Was your motor constantly going off and on?

 

This happens to me on the way home quite often.

If you are going uphill at all, even a little, and barely moving...you are using Electric power almost exclusively. Eventually, the ICE will need to kick in to recharge the system...significantly impacting your MPG numbers.

OR

If traffic is stop and go...but you need to pick up a little speed each time...the ICE kicks on each time because you are accelerating too fast for the Electric motor. The more times is kicks on, the worse your MPG will be.

In both cases, the terrain is the biggest factor. If the same situation happens to me on flat or downhill terrain, I am almost always in the 99.9 MPG range...and my MPG numbers skyrocket.

As you noted, this eventually evens out when you can pick up speed again, so there is not much you can do about it (it is more exaggerated when you are at the beginning of your tank because your average MPG numbers will jump around more...towards the end of the tank, it will have very little impact on your average).

 

I've found that when the traffic stops and stays that way for more than about 10 minutes, and I have the AC on at least a little bit, the battery will drain down to the 2 purple bars.

Then the engine starts kicking on and off, mpg gets ugly.

Sanity starts to slip... The situation is dire.

In comes the Garmin C550. I've had some problems with the sticky mount think holding to the dash, I'll get through that. The rest of it is pretty dang cool. I get in the car, punch in my 4 digit code (anti garmin theft), touch screen push "Where to" -> "Home" and it maps out the deal, tells me fairly accurately about what time I'll get home, and starts talking directions at me.

As I'm driving out of the parking lot, the thing is grabbing live traffic data off some FM radio station and putting up the construction zones and traffic tie-ups on to my route. If I suspect a slowdown / tie-up on 294 south, I work my way over to 53/355 south.

In the event of your tie-up, I'd have jumped off at the next reasonable exit.. I'd have had plenty of time to scope out the map to see if one was better than another. Basically pick any decent/big road off that tie up and the garmin will recalculate your way home.

In chicagoland, the traffic FM data feed only reaches about as far west as 355. I typically do have incoming feed there, but farther west (on 88), it drops off. I hope they have plans for pumping up the signal strength in the near future.

The GPS is more about saving sanity than saving money or gas. I'd have to avoid a lot of these situations to ever get the cost of the gps back in gas.

 

Yeah, If I get stuck in really bad traffic I try to turn the AC off and roll down all the windows. That way the car shouldn't drain to 2 purple bars (and start running even when standing still). It's easier to take in the morning. Coming home I sometimes cave in and run the AC standing still for long times even though it breaks my cool when the gas engine starts up.

My limit seems to be 93F outside.

 

I still remember one really hot day near 90 a few weeks after I got my new Prius. (OK every thing is relative, in the PNW 90's is really bad, 100 is unthinkable, global warming is going to hit us hard) I had the air on set at 69, hey this is the PNW, give me a brake. I got caught in a traffic jam caused by an accident. I had my first over 55mpg tank going and when I passed the accident I was under 49!

 

Here in So Cal it has been very hot. I did an experiment to see what impact my AC had on MPG. I drove my normal commute with the AC set on 72 for a tank while the daytime temp was around 100 (commute to work around 75 degrees, to home 100, lotsa traffic, use the carpool lane, 45 to 55 minutes to go 38 miles each way on the freeway, about 3 miles on surface roads). Anyway, with the AC, I was getting a shade under 50 MPG (49.7 according to Prius).

The next tank I roughed it and went with windows open and no AC. Temps were similar. I just ended that tank at 54.8 MPG.

Needless to say, I will be quite sparing with my AC when I can stand to not use it. When it is over 100, I'll burn a bit of extra gas.