First off, a little disclaimer. I am an engineer which means I am probably a little predisposed to being OCD and I can't ever get enough data. Since I purchased my 2004 TL(6 spd MT) in 2006 (used) I have been keeping meticulous track of the gas mileage. I compile the info in excel and I thought it was too interesting not to share. For reference, most of my driving is bumper to bumper stoplight to stoplight. I only have a 3 mile commute to work but that 3 miles takes 20 minutes every day! That said, I have over 100 data points from which these were created and using a second order polynomial line fit you get an R-squared of .9255 (for not stats people this means its accurate). According to the equation, the best gas mileage is around 50 MPH. Keep in mind this is using the data (MPG/MPH) from the car's computer so this means an average of 50 MPH for the whole tank. The optimum speed is probably around 55 (like we've been told our whole lives) or maybe even 60 since the car's computer takes running time while stopped in to account for the average. I also track the gas mileage to check the computer's accuracy so i'll upload that soon. I know this is mega nerdy, but since i did the analysis i thought i'd share in case there was another nerd out there that appreciates it. enjoy.

 

good job tracking your mpg, but could you post a larger picture?

 

Pic too small.


Do you have enough data points in the highway speed range? Say, 50 - 80 mph.

 

 

Your poll is missing a major area: I am satisfied with MPG. That would be my choice and it's not there.

 

I'm glad someone is doing this. I've been preaching forever that mpg is directly related to average mph. If I do pure city driving such as the 1.5 mile drive to work and back every day for a month, I'm down around 11mph and 9-11mpg and it's perfectly normal. The car gets the usual 29-31mpg on the freeway doing 65-70mph.

There's a thread around here where people posted their mpg vs mph and every TL was very close, I want to say within 5% of one another given the limited data in the thread.

I think a better poll would be a mpg vs mph poll to gather more data. Average mph rules over every other factor.

You have to figure the extremes. Normal acceleration from a stop light is enough throttle to maintain around 130mph obviously your results will vary. Try accelerating on a deserted stretch of road as you normally do but don't let off the throttle, hold it in the same place and see at what speed the car stops accelerating.

On the other end of this extreme is deceleration where rpms are above 800 and your foot is off the throttle and the fuel injectors are shut off. It's the only redeeming quality of stop and go.

This reminds me I need to look at my mpg and mph. I'll post back if you're interested.

Oh, and to the original post, the engine becomes more efficient as you increase throttle so in theory if you had a gear ratio that allowed low rpm with a lot of throttle or even full throttle to maintain speed; a speed that's low enough that aerodynamics and friction are not hurting you, that would be your best mpg. In theory it would be at the torque peak but I'm having a hard time with that one considering how high in the rpm range it is. With it being extremely flat in the TL, I don't think being at peak torque and peak VE is all that important.

I think I went off topic lol.

 

If your results track mine done on www.fueleconomy.gov, you will find that the MID is very accurate and only suffers from round-off error mostly: an actual MPG of 25.6 might round up to 26 or 25.4 might round down to 25 and the like. The MID is pretty accurate and should be since the fuel injection can monitor actual fuel movement.

 

I'm getting 17MPG.

I only do city driving, too.

 

Agreed. The ECU obviously has to be extremely precise in fuel metering to maintain the desired AF ratio, it obviously knows how may miles you've driven, it *should* be more accurate than a manual calculation other than the rounding that you mention.

 

To be more accurate than just "city", what is your average mph?

 

squinting a the graph, it seems pretty accurate. IIRC my avg. speed off the top of my head is around 37, my avg mpg is 27-28.

 

Just checked, and it's 23 km/h which is 14 MPH

 

According to the MID, the worst mpg I've ever gotten on a full tank was 17 when driving like a bat outta hell and 90% city and 29 when driving all highway 70-90 mph.

 

nice job tracking the results... bigger graph would be a plus

 

We've seen people get full tank results of ~32 mpg with a 65+ mph avg (by the MID).

I think the curve might flatten out more in the 50 - 70 mph range before it falls off again.

 

Ya, that is about right. 50-70 there is little variation in mpg's. I use to average 30mpg's before I put my 19's on. Now I'm lucky to get 26-27 mpg's at the optimum speed.

 

Hey Acurick,
I hear ya on checking MPG, especially with gas going up every day. I get roughly the EPA-listed numbers (20ish City/30ish Hwy) and am happy with that. Figure I can laugh all the way to the bank compared to my neighbors who get killed on depreciation by trading for new cars every few years. More power to them of course as they add to the state sales tax revenue...

 

There's the "city" again. What's your average mph?

That's good to know. Just looked at mine and it's 14mpg, 13mph. Luckily with a 3-5 mile round trip drive every day I can usually go 5-6 weeks between fill-ups. That's especially nice with gas being $4.60 a gallon locally.

 

I don't know for sure but I assume it would be around 15 mph. I'll test it after I fill up next time and take the back roads to work. What I have now wouldn't work because it is about 50% highway / 50% city.

 

I got 28mpg highway, and 22-23mpg city, on my wife 07 TL-S

 

I thought you might also find the summary data for 32,191 miles of tracking interesting. Below are my averages and also maximums for each category

AvMPG AvMPH Tot Miles AVG MPG Tot Gal AVG $/gal Total $$
21.98 26.4 32,191 21.59 1,499 $3.10 $5,103

Max MPG Max MPH Max Dist (mi) Max Mileage Max Fill
(gal)
29.0 68.0 402 28.4 16.439

I don't know why the pics i posted show up so small?? Help?

 

I sent you a PM.

 

MID Average MPG (MID)= 21.98 Maximum MPG= 29
MID Average MPH (MID)= 26.4 Maximum MPH= 68
Tot Miles= 32,191 (of data)
Average MPG= 21.59 Maximum MPG= 28.4 (calc'd from gas used and mileage traveled)
Total gas used= 1,499 gallons
Average Gas Price= $3.10 ($/gal for 91 octane in SoCal)
Total Spent on Gas= $5,103 (not bad since Jul of '06)
Max Distance on one tank= 402 miles
Max Fill= 16.439 gallons

 

06 TL unmodified:
-over 8800 miles on the MID since last reset, average mpg 25
-long highway cruise, 33 mpg at 65 mph steady with cruise control on
-I use 93 octane gas with ~ 10 ethanol (all you can get in NJ- there's no 91 octane available {unless at Sunoco, but not widely available}, and all gas has ethanol here, except for maybe 1-2 stations very far away from me).
-MID average speed: 39 mph
-for the size and weight of the car, I'm very satisfied with the mpg (plus, I drive very conservatively)

Final thought: if you think the TL doesn't get the best mileage, you're still better off keeping it and using it instead of selling and getting a hybrid as the upfront cost can be quite high and can take many years for you to collect on your investment. This has been proven in many articles on the subject. If your mileage isn't the best, change your driving style.

 

Hosted for ACURICK:

 

very interesting. so far i've found since my roof rack has been off my car...i still get about 18mpg for about a 23mph avg. must be my happy lead foot and my "spirited" driving. my hwy mpg's i suspect will go up much more dramatically without my roof rack. avg mph 55-60mph mpg's with roof rack (no bikes) yielded about 24-25, with bikes...it goes down to 22-23 same avg mph.

this type of data needs to be posted as a guideline for the other models as well. i keep reading about people whining about the mpg's in their MDX and failing to understand that the MPGs is reflective of the avg mph driven for a tank of gas. it is a 4500lb SUV for crying out loud not a prius. sorry for the tangent.

 

i've been driving with an empty rack (bars and fairing) and havent noticed much of a drop, averaging 70-75 mph i'm still just over 30 mpg (resetting the computer while at speed)

with a fully loaded rack, aerodynamic drag increases significantly at higher speeds. I'd guesstimate a 2-3 mpg drop with a bike on top going 75 mph. I'd never go that fast though with a loaded rack..

 

Wow....lots of work.

 

i had full upright mounts on my rack with a faring. i had no problem driving 75-80mph with both bikes up on top.

i haven't really ever complained of my MPGs anyway. i knew what i was getting myself into when i put the rack on the my car and when i bought it (that includes the premium fuel that both of them cars drink).

i think i just have a little bit more of a heavy foot. what can i say 6MT...fun to drive!

 

This is a perfect answer to the question that Math teachers always get: "When will I ever use this stuff in real life???"

 

Just as a reminder to guys, the graph doesn't necessarily say 50MPH is the best speed to drive at, it's the best AVERAGE speed! That means you have to factor in acceleration and braking speeds as well! If I'm right, that puts it at about 65 MPH as the ideal speed to drive at.

 

Can't believe the OP never broke 30. Anyways, I don't really agree with the "higher mph = better mpg" theory. Sure you will have higher average mph if your doing mostly highway driving. But the slower you drive on the highway, the better your mpgs will be. Remember it takes 4 times as much power to go twice as fast due to wind resistance. So driving slower on the freeway should net the best results.

BTW: In Vegas, driving 70mph on the freeway to and from work would always net me around an average speed of 45mph. I always maintained 30-31mpg. This was my sweet spot. I could go as high as 34 if I followed trucks or SUV's, but definitely not worth the risk of rock-chips.

I did manage 31mpg in the city once. And that was a 40 mile two way average. Average speed must have been around 25-30mph. The trick is to read the stop lights WAY ahead, and coast in gear as much as possible while using almost zero brakes.

 

Yesterday I cruised at 60 mph, and I'm geeting 27mpg.
ANd I had 34mpg before at 45mph