Absolutely dismal MPG...

I resemble that remark! Toward the end of summer I was getting 57. Actually this tank is down to 52 mpg with ethanol in the fuel and colder weather (30 degrees some mornings, 50-60 afternoons). I have a block heater for the AM commute and P&G when I can. Lots of variables are involved including how much short-trip Christmas shopping you are doing!

 

I agree; I got a flat and it was the little warning light on the dash which gave me enough time to pull off the freeway and onto an exit ramp...in less than 2 minutes after the light went on, the tire was flat, and I'm convinced that I wouldn't have felt it quickly enough on my own to avoid destroying the tire.

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I'd suspect that, if cold weather makes the warning come on, there's one tire that's significantly lower in pressure than the others. The system reacts to differentials in pressure. It's not a fault of the system, if it's working correctly and the tires are aired up as they should be.

 

Didn't you read? I said except when dark! SOME people use them as daytime running lights. Pointless to the extreme, plus annoying because it seems like people are trying to high-beam you. If you really wanted to make your car visible, turn em to the first notch position (with the rear and colored lights on)


The heater on means that the engine is ALWAYS on during the 3 mile commute.
Any energy not going to the wheels is a waste of gas. Think about it, the energy that comes from the battery has CONVERSION losses when being put into the battery, and again when coming out of the battery.

If your fingers are cold, wear some gloves.

 

Yes, drops in temperature decrease tire pressure. I think there are some rules of thumb out there about this, but I don't know exactly what they are. I just try to check my tire pressure once a month.

 

well, i think i've mentioned my average commute around here previously, but here goes.

i go a few blocks, probably 6, in town before i hop on the freeway. that's about 35 mph, and usually i can do this with no stops. then i'm jamming on the gas pedal (my choice, get over it ) and doing 70 on the freeway for just shy of 3 miles. i come to a complete stop and wait usually a minute for the light, because that intersection sucks. then i deal with 4 more traffic lights to route my way around the two hospitals and all their traffic. 30 mph for a few blocks, stop for a minute, repeat. by the time i make it to my usual parking spot, i'm in the upper 30s mpg for that trip. and that's when the temps are in the 50s. you see, it doesn't exactly get cold around here!

i've got the same tires at 42 and 40, run regular gas purchased from the BP down the street, run the heater at 74 when the temps are in the lower 40s.

my average goes up to 42 from my errands runs, which are a much more ideal drive.

 

Just food for thought...

 

Using your headlights during the day makes your car more visible to other drivers. If your car is more visible to other drivers they are less likely to run into you. Sure, someone staring at your car will see it. But that's not what happens: Some guy in a hurry is looking for a break in the traffic, glancing this way and that, taking a half a second to look in each direction; your car is moving along at the speed limit, and his eye just doesn't take it in. Headlights jump from his eyeball to his brain in a way a car without headlights on does not.

In some countries (like Canada) it's required to drive with your headlights on, because it's safer. If you want to save one ounce of gas per week by leaving your lights off during the day, you have a legal right to do so in the U.S. But you are making yourself just a little bit more likely to be hit by some guy who's just not quite paying enough attention.

As for the heater, yes, it causes the car to burn a little more gas. But I sure as hell am not going to drive without heat when it's 20 degrees below zero out! And I repeat, it's pretty darned anal to freeze your buns off just to improve your FE by a tenth of a mile per gallon, though at least that hurts nobody but yourself.

 

Heh. That's fine too, whatever floats your boat. However, I should point out that with my driving style, drivers have a HUGE gap to merge into my lane if needed. The gap I leave must be at least 6 car-lengths long...

The reason why I leave such a large gap is to reduce traffic waves and smooth out the flow of traffic.
see: http://amasci.com/amateur/traffic/traffic1.html

And who's to say I'm actually hurting anyone else? Out of the 5+ years that I've been driving, I have yet to hit anyone or have anyone hit me. (aside from door-dings).

Every second that the ICE is on DROPS my mpg by like 1mpg... Granted I do not live in negative 20, so I can't say if I'll turn on the heat or not.


Anyway, I see no reason why your attacking perfectly valid reasons to increase MPG. In order to gain something, you must sacrifice something else. I dare say this is true for almost all hypermiling techniques... Be it the feathering technique (tradeoff of increased concentration and control), or grill blocking (cost of materials, risk of overheating)

 

Okay.

If your weather is very cold, and your commute is very short, that could certainly explain it. The best test might be to take a longer drive and see if it improves. I'd expect 25 mpg for the first 5 minutes, and up over 50 by the 3rd or 4th five-minute segment.

 

So, an obvious question here but I don't think I saw an answer to it yet in the thread - have you taken the Prius into the dealership to have them take a look at it? It'd be worth the expense just to make sure all your bases are covered. Maybe there's some non-obvious internal issue at play.

 

I'd try taking it for a longer drive at highway speeds (30+ minutes). If your not getting at least 45mpg at 60mph after resetting the display in the middle of the drive, then something is wrong.

Also, you might wanna try and stop for like 6 seconds at the "turn around" point if you do drive it for a full 30 minutes on the highway (to enter stage 4).

 

Of course, the "something is wrong" might be that you live in a place where the weather dips below 40.

 

does she have any highway runs or is this just a lot of city stop and go? a block heater will help universally, but blocking the grill may not be a good idea depending.

 

Good to hear it wasn't anything to do with the car (I.E. nothing is broken).

 

Forget about it!!! With a very short commute she is burning a very small amount of gasoline. Let's say she's burning 1/2 cup of gasoline. You could maybe go to extreme lengths, and demand that she drive in an exotic but unsafe manner (such as the famous pulse-and-glide) and cut a tablespoon out of that half cup. What have you really accomplished other than bragging rights that you're getting 29 mpg instead of 27 mpg?

Here's the real insanity: Some people drive EXTRA miles in order to show a higher average MPG. They've earned some bragging rights at the cost of burning EXTRA gasoline unnecessarily.

That's just anal.

Very short commute = very low gasoline consumption, in absolute terms = GOOD!!!

Just drive the car and enjoy it.