Does anyone have any tried and true gas saving tips for the tc?

I have documented all of my gas usage since I got the car, and I can state the following:

I live in Texas, The data I am using for comparison is from last summer compared to this summer in the same length of time (to use a consistant temperature assumption and consistant driving conditions).

The car is a '07 tc automatic. Flint Mica. No spoiler. Mainly highway travel (65%).

The conditions from last summer to this summer that I changed are:
2007 - Normal Driving Conditions filling up when the gas light comes on.
2008 - Slightly more conservative driving (not accel too fast out of lights, shifting to neutral to a stop sign from far away, driving closer to the speed limit, etc) and filling up at half a tank.

The gas mileage per test:
2007 - 28.05
2008 - 30.63

As you can see, thats a 2.5 MPG increase. Pretty good if you ask me.

If filling at 1/2 a tank doesn't help the MPG (which I believe it does) it still makes sense to do during the current gas price increase. Consider this example as proof:

Assume gas prices are increasing 1 cent per day. And you drive one full tank per week. Assume one full tank to be 13 gallons.

Full fill up:
You have a full tank on Sunday and gas prices are $3.709 , and drive all week and have to fill up on the following Sunday. So you fill up completely Sunday. Prices have increased by 7 cents (7 days x 1 cent per day). You fill up your tank at (13 gallons) $3.779 for a total of $49.13.

Half fill up:
You have a full tank on Sunday and gas prices are $3.709 , and drive normal all week but fill up at the halfway point, lets say Wednesday. You fill the car up (6.5 gallons) at $3.749 (4 days x 1 cent per day) for a total of $24.37. So you continue your week and fill up completely again Sunday. Prices have increased by 7 cents since day one(7 days x 1 cent per day). You fill up your tank (6.5 gallons) at $3.779 for a total of $24.56. Your weekly total cost is $24.37 + $24.56 = $48.93.

As you can see there is a savings here:
Full tank - $49.13
Half tank - $48.93

Note that this is when the gas prices are INCREASING. If they are going faster than 1 cent per day you will save even more. Extend your $.20 savings over the year and you save: $10.40 !! Whoa! 10 bucks! Haha, its not that much, but I also believe that it increases gas mileage, and thats where you save your money.

Assuming you get an extra 1.5 MPG on your current 27 MPG driving habits for half filling, you would be saving:
1.5 * 13 gallons a week = 19.5 extra miles a week.
19.5 * 52 = 1014 extra miles per year.
At 27 MPG .... 1014 / 27 = 37.56 Gallons per year
At a cost of $3.799 per gallon - 3.799 * 37.56 = $142.69 savings in one year

So the $10 isn't much, but the 1.5 MPG increase is $142.69. So a total of around $150. Not too bad for filling up half the time.

Note: if gas prices are decreasing then the half fills would actually cost you money with regards to price fluctuations. But that amount is no where near as relevent as the MPG savings.

Even if you don't want to do the half fills, you can see that being a little more conservative with driving habits can save you big money. If you currently get 24 MPG, I know you can bump that up to at least 28 just by driving habits. Thats $370 in one year! You could easily get some more mods.


I am also going to try out some other gas saving tips. If anyone has any that they want me to prove/disprove I will try my best. I am currently looking at temperature changes (when to fill up), car storage (does heat affect the gas), speed of filling up (the pump speed), and time of week and time of day. I like to play with numbers as you can see. Sorry for the long post. Let me know what you guys think.

 

How fast is your highway travel? That will make a big difference. You'll save a bit more at 65 (or lower) than you would at 75 (or higher). I usually drive the speed limit on the highway now for that reason.

The easiest things make the biggest differences:
- slow down
- clean the extra crap out of your car (less weight = good)
- keep your tires properly inflated (check pressure first thing in the morning)
- make sure your car is aligned properly
- ditch the big, heavy wheels for OEM or lighter

I'm sure there are more, but that's the easiest kind of stuff.

 

Oh ya, about the savings. I don't think the half tank thing is even worth it unless it's really skyrocketing (which it isn't right now). $.20 a week isn't really a whole lot of savings. And neither is $10 a year.

Of course squeezing out another 1.5-2 or more mpg per tank is always a good thing.

I've been tracking all of my gas spending on brianbauer.org and in my google docs (i have a spreadsheet with all gas purchases and a bar graph year over year from mid 06-present).

 

I just checked out that website.

The tc manual reports were not very impressive. My current MPG for the life of my car is 28.130.

I have also seen trends of better gas mileage in the summer than in the winter. Thats odd because A/C vs heater should be the other way. Therefore there must be a link between temperature and gas mileage. Maybe global warming will be a good thing?

 

drive to work only.
then go home and play Forza 2 all night.
if you want to go out make your buddies pick you up. haha

ive saved a ton of money in the past couple weeks doin that.

 

Haha... the 05 tC reports are about 99.9% mine. There were like 5 on there before I started. The rest are mine. I'm not very frugal many times with my gas. Plus that includes multiple autox events each summer. There are a few road trips on there of 30mpg or better.

 

I can't agree with the half tank - full tank fill ups... gas is weight, and more weight means less efficient mileage... cars will usually get better mileage with less weight than the same car with more weight... so the more often you drive with less weight, the better your mileage will be...

Now, if you want to take this to the extreme... save money AND get better mileage by filling it up TO HALF a tank of gas only when the light comes on... now before you start lighting fires and burnin' me... I would only suggest this if you drive short trips during commutes... my M-F commute is usually only ten minutes away.

Also on coasting to a stop... not only is it illegal in most states, but your car is actually using more gas to keep the car at idle (in neutral) versus less gas being used during decelerating in gear.

 

QFT. Decel = 0 fuel used. Nuetral/idle = enough fuel to produce roughly 5-10hp.

Also, I wonder if anyone has gone as far as installing a fuel/ignition controller and slightly leaned the car out at cruising speeds

 

You can throw out your 2008 figures, your gas gauge is not accurate enough to be used as a reference.

The proper way to track mileage is to fill your tank until the pump shuts off (ideally the same pump at the same station every time) and reset a trip odometer to "0". Next time you fill-up to shut-off, divide the trip odometer reading by gas pumped = mpg.

By filling up to anything other than a full tank there's no way you can accurately calculate your mpg's since you won't know how much gas you're actually burning.

 

^ Yes there is, it's called look at the receipt and see exactly how much fuel went into the car. Then keep track of how much gas was used and how many miles were driven.

 

lol.
wasnt there a thread exactly like this a while ago the went terribly wrong?
haha.

its started out just like this.
Mid lifes comment
carbons comment

then a fkin nosedive to isht ville.

 

I don't recognize his name, so I don't think it was me. But still, lol.

 

Mid_Life,

Yes you are right. But the entire time I have had the car, I have filled up to when the pump stopped. I never top off. I also mark down the city the station was in and the station's name itself. Every time I fill up, I fill it to the top. The half fills are when the fuel gauge reads 1/2 full, then I fill up.

I thought if you have the tank less filled (between 0 and 1/2 filled) you would get better gas mileage. However, there would be no way to prove it because you would be guessing when the tank got to 1/2 from 0. So to prove it, I took it the other way. If my average is say 28, and the TOP half (1/2 to 100% filled) gets less than 28, then that means the bottom half would be getting more than 28, to average it to the 28. But that is not the case. The top half actually gets around 29.5-30. It's strange that it worked this way.

One explaination that I have found is that the gas is more succeptable to evaporization when there is less in the tank. As a result, the gas will evaporate when you tank gets lower and then you have less fuel to run on. I don't know if this is true, but since the top half of the tank is giving me better results than a full tank, I am going to keep doing it.

Now when I fill up at the half way mark it is not always 1/2. The full tank is usually12.5 to 13, and the half tank trick is usually around 8 to 8.5. The tc has a 15 gallon tank I believe so its a little more than half each time. None the less, its working in a positive favor so....

 

14.5 gallon tank

 

no i didnt mean you guys specifically. lol
i just meant that the two comment you guys posted were exactly like what was said last time right before the thread went to isht.

 

Ahh, lol. I'd still like to know if anyone has used fuel management to run a little leaner. If I could hook up my wideband to my stock s-pipe (not welding a bung in it) I'd run my F/iC and lean out my car to see if it helps with gas mileage.

 

I drive it like I stole it. Oh, wait. You said gas SAVING. Nevermind.

 

How can you say you aren't frugal with your driving yet you're hitting 30 mpgs?

My tC, at its worst, has gotten as low as 16.5 - 18 mpgs. I then started driving much more cautiously, and now I'm consistently getting 22-23 mpgs. Granted, I'd say about 80% of my driving is city. Only things done to the car are Injen intake and Injen exhaust. I do like to go quick on the thruway from time to time, but for the most part not past 80 or 85

Right now I'm driving an 07 G6 GT and it has a mileage indicator, I really find that useful and wish the tc had that too

Gas prices suck but I can't find myself cruising along with gramps in his buick

 

I'm an aggressive driver and I get 25mpg with 18's, A/C almost always on and windows always open, so 30 doesn't sound too hard to get. In my 05, I got 29.8 mpg driving from Phoenix to the Grand Canyon, cruising at 105 the whole way.

 

invest in a scangauge.
and your wish will be granted.