jokerman826

I took a buddy to the airport today in my 2004 TL. On the way back I decided to reset the trip meter while driving. Over thefollowing 19 miles, I averaged 65mph and 35mpg. By the time I took the picture the average speed was at 64, because I exited the highway and was at a red light. But even so, the mpg was great considering the car is 8 1/2 years old. Also the A/C was on the entire time, which makes it even better.



Needless to say, I am very happy about the mechanical and physical condition of my car. So I figured that I would post about it.

mr2td

It's impressive the kind of fuel economy you can get if you are watching your speed and drive smoothly. I've seen similar results from 100+ miles of 55-65mph driving.

Aretardedorange

iTrader: (2)

I get 16 lol.

justnspace

iTrader: (1)

awesome to see you post, jokerman

jokerman826

i post her and there, a lot of times when i feel like i can contribute to something, someone has already posted what i wanted to say, so i just dont post anything.

lleron

iTrader: (1)

I don't know if I fully believe the trip meter. I always reset it when I fill up with gas and it always seems to be significantly off upon the next fill up. Last time it read 28mpg over 350 miles while I actually calculated 26.5. I would take what it says with a grain of salt...

gwiffer

iTrader: (7)

Although that's great efficiency for a V6 luxury sedan, it's trivial to post fuel consumption over such a short range.

Was the return trip a descent? tailwind?

jokerman826

I have done the manual calcualtion a few times before with my car and each time it was within a fraction of a mile.

I dont think its trivial. The short trip was mixed between flat, up, and down. At the time there really wasnt any wind either. Also I will not be doing any long distance driving for another month when i leave the chicago area and drive to Norfolk.

I hate cars

The MID has the potential to be more accurate than manually calculating it.

The mpg is impressive but if there was enough mechanical wear to decrease mpg over new, you would have serious problems. MPG won't do down due to wear for a loooong time. Good mileage means the 02 sensors and such are in good working order.

Glad to see it's still going strong at that mileage. Mine is "only" at 108k but still runs like new. I hope it continues that way.

TLtrigirl

iTrader: (1)

your AC has no influence on your MPGs....just FYI. if it does...it's negligible.

AirForceFX

Really? How so?

I figured from research and experience that in its simplest form, a harder working engine burns more fuel. I drive from Shreveport to Dallas once a month. With the AC on, I average 30-32 mpg. Same trip, same day, hours later (meaning similar temperatures, weather conditions, traffic on I-20) with the A/C off, I average 35-36. Unless that is your definition of negligible.

OP: It's comforting to know that my TL will perform long into the future.

TLtrigirl

iTrader: (1)

http://www.autoexpress.co.uk/news/au...thbusters.html

http://money.cnn.com/2007/05/09/pf/gas_myths/index.htm

everything is debateable. quite frankly i dont' care if the AC is eating my MPGs or not. i don't blast my AC unless it's painfully HOT outside and inside the car to cool the interior off. after that i set the AC fan at the lowest setting once i'm comfy.

jokerman826

I am not even at 74K on the odometer. But i have seen cars that are younger and have just as many miles get less fuel economy. even new cars arent even rated as good.

Also, the A/C does affect mileage, when the clutch of the compressor kicks in, it bogs down the engine, so in order for the engine to maintian the proper RPM it has to get more fuel.

This was a "Myth" for a while. Where your economy is the same or worse with windows down vice running the A/C. But it has been proven that the a/c does affect the fuel efficiency of a car. Its even on video from Myth Busters.

I cant wait for my drive to Norfolk. It will be almost 1100 miles, so i will see how it does in the long run. I havent done a long trip in almost 3 1/2 years. And this trip is going to be through mountains.

Steven Bell

iTrader: (2)

Well done, Joker.

I hate cars

I don't know why but I thought your car had 160k+.

I get 13 on average but it's apples to oranges. My average speed is 12mph. I can show a 35 mile drive that reads >50mpg if I reset the trip odometer on a certain stretch of freeway. At a minimum you need to do a round trip to make it accurate.
The compressor takes roughly 5hp when engaged so it takes "5hp" worth of fuel. It would be easy to figure out and then compare to the duty cycle to get an actual figure. Whether or not it takes more fuel to run the compressor or roll down the windows depends on the car/speed/etc. 5hp can be significant considering it takes about 30-40hp to maintain a steady speed down the freeway. Windows down does make a difference, I've made back to back 1/4 passes a couple times with the windows accidentally down and it hurt my mph by 3-4mph.

splew

I get about 27-28, but then again I cruise at around 80 on the highway. Not too bad.

Pat04TL

Is this enough range? If you can get MPG = MPH, now you're talkin'.

I hate cars

That's pretty good. I bought my TL new and did not reset the trip odometer for the first 48k or so. Mine was at 29mph/26mpg so somewhat close. That was also about the time I went with wider, softer tires.

Pat04TL

Yeah, the TL is a darn efficient machine if you treat her right...

JJH

iTrader: (1)

Blows my mind how the guy above is claiming to average 35-36 mpg in a Type-S. With all of my stones in order, the best I can get on the freeway round drip is 30 in my 07 type-s. Something that may be effecting me is the K&N air filter. He may also be manual, I don't know. I'm 5AT.

lleron

iTrader: (1)

I remember reading this in other threads on here and was surprised mine is as off as it is. Both times I've manually calculated it I used the same gas station. It's possible, although pretty unlikely, that they're shortchanging gas. I'll try a different station next time.

And I fail to see how the computer can be more accurate than manually calculating MPG over a long distance (at best I could see it being the same). I would imagine he computer is performing the calculation using duty cycle and averaging it over time. I could see this being a few % off, depending on sampling rate and the actual resolution of the duty cycle measurement.

LaCostaRacer

The MID is very accurate. I have almost 6 years of data for my car that shows that the MID is +/- .5 MPG of actual. Since my MID displays whole numbers that's the best it can do. I agree that the MID could be more accurate than real world numbers because of the variability in gas temperature when pumped and with actual dispenser when it clicks. The MID measures actual fuel consumed and knows the actual miles driven as well. As long as there is no fuel leak it should be pretty accurate.

We are planning a CA to CO road trip some time this summer so that should put about 3000 on the TL that has never crossed state boundaries before- should boost the lifetime average a bit.

I have a 20MPG life time average which jives pretty close to the 21MPG combined average of the EPA for 2006. Best MPG was 31.3 with an average speed of 70 and 272 total miles on tank- that was an impressive run to the Bay Area 4 people and luggage!

TheLowLife

How many miles are you guys averaging on a tank?

LaCostaRacer

The tank range answer depends on your comfort level on how low you want to go on the fuel. I usually fuel up just before the light comes on and this is about 250 miles.

You can do much better on the highway and get around 350 miles. The problem I have on the highway is that gas stations can be spread apart and there may not be one when you really need fuel- that's what happened on my 31.3 MPG run plus I knew the numbers were going to reduce when I hit the mountains.

TheLowLife

That is the answer I was anticipating. I normally fill up around a half tank, but, I let it go to the light just to see what kind of mileage I was getting out of a tank. I believe it was around the 260 mark when the light came on. I at first thought that was a little low, apparently it's average/normal.

DeathMetal

iTrader: (2)

117,000 miles, about 340 - 360 miles per tank. About 26 - 28mpg.

New tires should bump me up even more.

narnia

My 2004 5AT has almost 160K miles on it. My MID says I average 31mpg, and I'm getting 468 miles to the tank. I think this is accurate because I drive 70 miles x 6 times = 420 miles before the light comes on to let me know I have 45 - 48 miles to go before the tank is empty. I mostly drive on the highway at about 70mph. Even though we need to pay for premium gas, I'm happy with how fuel efficient this car is.

Undying Dreams

iTrader: (3)

I say the A/C does make a difference, I made 25mpg in my S10 coming from NC, the weather was nice and we had the windows down, as it got hotter we used the A/C and the mpg dropped like a brick. Haven't tested it in the TL yet. Regardless, nice job OP, keeping the TL clean and running smoothly, I get 24mpg in the city. Made like 330 off my tank.

I hate cars

I did something like 508 or 528 once. From here to Phoenix. I topped the tank off until there was fuel sitting in the filler neck. Didn't stop once and did the speed limit the whole way. If traffic was slowing I was coasting way ahead of time. I don't think I hit the brakes once.

AirForceFX

We may be driving a little different as well. My car is totally stock and it is a 6 speed. But even then, I tend to short shift and slowly accelerate up to highway speeds. I also run 65, except for the 70mph speed limit sections so I'm not unsafe to other drivers. That easily breaks into the 35+ range on my car. Validated by the pump.

JJH

iTrader: (1)

Good for you man! That's awesome mileage. Even if I drive like a grandma doing all of the obvious gas saving tid bits the most I can get is 32mpg.

lleron

iTrader: (1)

The CTE of gasoline is 950ppm/degC. That means that if the temperature of gas were 10 degrees C different from one pumping to another that would result in a maximum error of .01 = 1%. Gas stations are also supposed to have their volumetric output calibrated and checked by the state every once in a while so that should also be relatively correct. If the calculation is done by hand it should be off by a few % at most.

Regardless, that doesn't explain why I was 1.5 mpg off from the MID last time I checked. I would imagine it would be more accurate than that.

LaCostaRacer

^ The main reason may be that each gas pump might 'click' with different pressure. I don't know if they calibrate when the auto-shutoff occurs. I usually do 3 more squeeze/clicks of the pump and then call it a day on a fill-up.

To be sure, you would need to fill up the tank to a visible spot in the filler neck to be most accurate. That will take a toll on the charcoal vapor filter and isn't worth the trouble to do- I would just trust the MID to be more accurate than my filling consistency and call it a day.

LaCostaRacer

FYI, I haven't entered my last set of data but the below list from january to end of march should show what I'm talking about regarding the MID and it's accuracy:

date miles gals cost Actual MPG MID Data (speed & MPG)
01/06/2012 206.30 10.560 40.13 19.5 mph=28;MID=20
01/16/2012 206.10 11.280 42.86 18.3 mph=26;MID=18
01/27/2012 224.60 12.070 45.86 18.6 mph=28;MID=18
02/06/2012 218.80 12.390 48.31 17.7 mph=24;MID=18
02/20/2012 250.30 13.164 55.28 19.0 mph=26;MID=18 ***
02/27/2012 235.50 11.700 52.17 20.1 mph=28;MID=20
03/12/2012 250.60 13.253 59.63 18.9 mph=27;MID=19
03/22/2012 243.70 11.940 53.71 20.4 mph=30;MID=20

As you can see it's pretty accurate being off just 1 MPG at most. This data was posted on my account in www.fueleconomy.gov.

I hate cars

The only way to be even close to accurate manually is to average mpg over many fillups. A single fillup can be off by nearly 20%. You're at the mercy of the pump's shutoff point.

Injector pulse width vs mileage is a very accurate way of calculating mpg. Even the fuel level sensor in the tank is very accurate in modern cars. Its still susceptible to external influences like ground level just like the manual calculation but you're still eliminating the pump shutoff point from the equation. Some manufacturers use this input for this calculation, some do not. Obviously better resolution for the readout would be nice.

lleron

iTrader: (1)

Haha, fair enough. I didn't really think about the pump shutoff point. I used to work a decent amount with instrumentation, and as you can probably tell I still find it interesting.

opboarding

Very good points. I would assume that gas stations are as close as possible to being outside of the legal tolerances. If they can give you a few % less of a gallon and still legally call it a gallon, why would they try to give you any closer to a gallon? That along with the shutoff point, who knows what you are really putting in your tank each time you fill up.

My fill ups are usually like 5% lower than what the MID says. The MID is closer to what I'm really getting but my wallet doesn't get any of that benefit

Also, this site is pretty fun. I've been tracking my car's MPG since it's first fill up. It makes nice graphs and stuff.
https://www.fuelly.com/driver/opboarding/tsx

BrownBuck

I've never gotten better then 27mpg and that didn't stay like that forever.

The way i figure is everytime you drive you avg differently. MID calculates your overall avg for the whole tank. When i fill mine up and do a reset right before i start driving from the gas station it usually says like 9-10mpg then i go to highway and it slowly picks up. Depending on how far i drive on the highway i usually end up around 27-28mpg( aprox 38-40mph) the speed is funny cuz i only did 25-30mph for maybe .1 mile before hitting the highway where i do 65mph+ consistnatly w/o stopping and it still shows me my avg speed is about HALF what i really have done.

Anyways...my light comes on around 300miles +/- 10miles depending on how hard i drove it and how much city i drove. and when i fill my tank it takes aprox 12-13 gallons. so VERY roughly it gives me around 23mpg if i do 13 gallons over 300 miles. My MID almost always has shown me 25mpg when i'm filling my tank.

::shrugs:: the way i figure if i can get 50-55 bucks per tank and it lasts me about 10 days that's 150/month i use to do 120/month in my 99 camry(haha yes) so i'm happy!

BrownBuck

Whoa that's cool as hell lol i might use that website!

94eg!

Didn't read the whole thread, but thought I would chime in on the subject: Start tracking your mileage on Fuelly.com and get the real story. Resetting your trip for a short drive doesn't tell you shit. And even resetting it every time you fill up doesn't help you track the history of the car and identify problems.

BTW: I have a 23 yr old CRX Si that just got 43.2mpg. And that's not even factoring the tires I'm running are 3.2% taller. That boost's actual mileage to 44.5mpg. lol If you take care of these cars, they will last. The same can't be said for any EV or Hybrid. How long does your car's battery last these days (3-7 years). How long do you think a Hybrid's battery pack is going to last. 10 years would be lucky lucky. And who is gonna replace an expensive battery pack on a 10yr old car?

I just started on Fuelly.com a month or two ago. It's really interesting to track your results. Plus they give you banners with built-in links you can share on the forums (see below). Here are my 4 cars so far. CRX's average isn't that great because it had a bad gas cap seal that let a lot of gas vaporize over winter storage. This site helped me figure that out though...