I have a '08 TL Base with no engine modification except for the Type-S quad catback exhaust with 3rd muffler delete.

Is this the typical mileage for the 3G TL? I also have a '10 TL and that gets ~23MPG. How is it that my 3.5L TL gets better gas mileage than my 3.2L TL? My brother's '05 Tl gets him ~ 22MPG. I know they both have the same tranny, so that can't be it.

Is it because I put on the Type-S exhaust? Did I need to recalibrate something after puttong on the quads? Please help... Premium Unleaded gas here in SoCal is over $4/gallon.

 

Lots of city driving? Heavy foot to hear the exhaust?

 

Here's the basics checklist for seeing what's going on:

1. Are you running premium fuel?
2. How many miles?
3. Have you used any sort of fuel cleaners or additives?
4. What tires do you have?
5. What is the current air pressure in the tires?
6. Do you have any modifications like a sound system?


If you run regular fuel or don't run premium (or use bad premium that's been sitting for a while and has a LOT of ethanol) then you will get BAD gas mileage and may do damage to the motor.

Depending on the miles you have on your car, you may need to clean up the intake manifold and throttle body to help it along. If you have used certain cleaners or additives it can make the problem worse while others can make the problem disappear!

Depending on the tires you have, it can make a large difference in MPG. As well your air pressures can make a HUGE difference. If the tires are low on air, then the car has to work harder to move them. The optimal air pressure is 35 PSI COLD!

Please answer those questions and we can help!

 

Answers are in blue above. Any help is greatly appreciated

 

gas quality is not the question here. I've filled up with Arco and at it's worst my TL has never gone below 20 average for street driving.

 

it all depends on where you drive....when I drive on the highway i get 29mpg....when i drive on my college campus (lot of stops signs lots of traffic lights) I get 11 mpg and thats a constant 11mpg

I have pretty heavily modded too and I can get easy 28-29 mpg on the highways because I maintain one speed throughout the entire time

 

i have a TLS and i have the same problem.. premium gas, correct air pressure, 45k miles.. automatic.. getting 12mpg in city.. regular driving (shifts under 3k rpm).. highway 26-28.. but i never drive on highway.. i have no modifications on the car.. its a stock TLS.. wthhh

 

Driving habits or style probably has one of the biggest effects on your mileage. Not just freeway or city (which matters) but how heavily you accelerate. You're not driving a motorcycle, these cars have a lot of pounds on them and momentum is incredibly important. Maintaining a constant speed will help your mileage. Heavy acceleration and lots of "accelerate, brake" cycles when you're driving aggressively in moderate traffic will eat gas like its nothing.

Try playing around with your trip computer some time.. if you have any roads near your house with a 50 mph speed limit, reset it just before the light goes green and check out the difference between acceleration with your pedal pressed in 1/4 vs 3/4. Then reset it while cruising at 50-60 mph with cruise control on and see what numbers you get.

Obviously with such a short period of time (20 seconds of acceleration or a couple minutes of cruising) you'll get a large variance and its not great data for comparing to someone else, but it's an easy way to show yourself just how much your driving patterns affect mileage.

For reference, if you can sit on the freeway at ~63mph on a flat stretch for at least a few minutes (reset the trip computer after you've got cruise control on).. I'm getting about 33 mpg. At 75 mph (again, cruising with no fluctuation in speed whatsoever for several minutes) I'll get about 29. This is in a TL-S.

 

if your mileage is that bad, you might want to consult the dealer and see if any warranty can be applied.

but more than likely, i suspect it's your driving conditions and/or habits. i go mostly freeway, but i average 21/22 overall even though my freeways are at 29mpg.

and for some reason that i have yet to find out why, whenever i change anything to my car (even like an oil change), i get a drop in mpg for the next 3-5 tanks. i think i need to reset my ecu.

 

When was the last time you ran some Seafoam through your fuel system? Try throwing a can in your gas tank. Follow the instructions on the can to a "T". Worth a try and it's good to keep your injectors clean anyway.

 

12 mpg?! Thats like a ferrari! Yup, throw seafoam in the tank for a cleaning, it works! I'm getting 17 mpg city in my TLS.

 

Let's start simple-

What are the MPG and average speed off the MID? And after how many miles traveled (complete tank run-through is preferred)?

 

Just ran my '08 TLS the full length of the Garden State Parkway and pulled down 30+ mpg,, better have your car checked.

 

I have a base 08 TL and I get around 17 mpg in city driving.

My average speed is around 20 mph according to the trip computer. Wish I knew how to get it closer to 20 mpg. My 2nd Gen TL and my wife's Pilot have better gas mileage.

 

Before getting into solutions there might be an easily explained reason for the MPG issue. How about the most basic question: What MPH value is the MID reading in addition to the MPG value that you're already noting. Is it < 25 MPH? If so you probably don't have a problem- try not idling your car as much. I find it hard to believe that a newer TL with the exact same MID MPH reading would yield a significantly better MPG but I could be wrong if the new TLs have cylinder deactivation.

 

Costco and chevron probably have a lot of turn over so I doubt your getting stale gas. With 40K on the car more than likely with a bit of city driving that there is some buildup in the injectors and other parts of the engine. I'd throw a bottle of Redline SI-1 fuel cleaner into the gas tank and also look into the "sip sip" method of putting seafoam into the engine.

Also 33PSI is okay, but like I said before bumping it up to 35 should help out a LOT with gas mileage.

The Falken Azenis don't have such a high level of rolling resistance vs an Super Duper High Performance tire so that's not really cutting down on gas mileage.

What will make a large difference in MPG is your driving style. Simple things to conserve gas will help out a bit. For example if you see the light has been green for a LONG time, is turning yellow or is red, DON'T accelerate towards it! Simply let off the gas and let the car coast to a stop! And sometimes you will get lucky and time it just right to where your rolling around at say 30 and the light turns green! Then you will use less gas to get back up to say 45 than starting off from 0!

Also keeping the RPM's under 3K is a good challenge to also entertain yourself while driving in city traffic!

 

Our TL is heavy as f@&k. I do mostly city drive and I was averaging 12-14 mpg and I was mad like hell cuz my friend corvette average 19-22 in all city drive! What I did is loose my spare tires, front and rear 5 mph bumber, useless trunk cover, engine cover and other useless stuff that my car have. I put new air filter, balanced my tires and change my driving style to grandma mode and my mpg improved a lot. Now Im averaging 19-21 mpg in all city drive.

So yeah just don't brake a lot and and dont slam your gas pedal (no more 3k rpm) and follow csmeance's advice about the driving style.

 

Man some of you guys are getting horrible MPG. I think driving style is at fault.
I average 17-20MPG in the city. And 28-31 MPG highway.
04 all stock on 65K. I do maintenance asap on everything so that might helps.

Are you using thicker oil?

 

This:
this:
and this:
Our TL is a fairly heavy, but aerodynamic vehicle. I've a bazillion of these MPG threads, the bottom line is usually the same:

• People get great mileage on the highway -- anywhere from 26-34 mpg. This is due to the aerodynamic design. Doesn't take too much gas to keep it moving once it is already in motion.
• People get terrible mileage in city driving -- anywhere from 12-18 for people doing a lot of stop and go. The car is heavy so it takes a lot of gas to get it going.
• You can check a few of the suggestions above (tire pressure, clean engine, oil thickness, etc) and they may improve MPG a little, but probably not much more than a few MPG.
• The biggest improvement you will get is from change in driving style. Keeping the RPMs below 3000 isn't as much fun, but it will help gas mileage tremendously.

Good luck!

 

and coast when possible. Dont accelerate towards red lights only to brake. Use your depth perception and judge the distance. Coasting above 900 something RPM (lets just say 1k) shuts the injectors off while you engine brake.

In Irvine since speed limits are 45+ on main roads I can start coasting a quarter of a mile away towards a red light and by the time I get to the first car in my lane it's green. Just saved that much gas coasting and wasted zero on heat and dust (braking).

 

lol no more flooring the pedal for me for now . I used to get at least 15mpg city driving now i get about 22mpg. Not bad. How can i do a fuel system clean up using the cleaner? Is that something i can do myself or a mechanic?

 

^with seafoam?
read directions on how much to pour in the gas tank.

 

Is that a brand? What exactly is it? Sorry i'm not too oriented when it comes down to that field of the car .

 

 

04-06 tl has a DIFFERENT tranny than the 07-08. the 07-08 got an updated tranny from the RL and is same for type s too.

arco is not a top tier gas so i tend to avoid arco whenever i can. not that im blaming the gas for the low mpg, just making a statement here.

 

I used to got 12 and now around 15-18 so it's normal to me. How I drive ? Usually little bit hard with AC 68 F second level.

 

yea my point was that even with what some people consider terrible gas my mpg doesnt dip below 20. the OP's issue isn't gas related for sure. I personally have been using Chevron lately since my Chase CC gives me 5% cashback which basically makes it as cheap as Arcos.

I would look into driving habits more. Low mileage TL like that shouldnt have anything wrong with it even if it wasnt taken care of properly. All it would have needed since new are a few oil changes, and some minor things like tires, brakes, and rotations. None of which would have significant impact on mpg.

 

I have my oil changed every 3K. I guess I'm a little heavy footed now after the type-s quads were installed. 1st gear feels a little sluggish off the line.

My first guess was the exhaust piping on the type-s exhaust is a little bigger than the base exhaust; thus requires more gas to be applied to pushed thru the bigger exhaust. I'm probably off base here since I'm no expert nor master tech.
I was expecting 17-20 miles city, not 15.

I'm going to try the seafoam tomorrow.

Thanks for all the tips. My hope is to get 19 city/24 hwy. Not too much to ask, is it?

 

I would get horrible mileage (12 mpg) in the winter when I was only driving a mile or two in the cold to class then turning the car off. But now, driving to work in the summer, I get between 19 and 21 mpg city and about 30 on the highway. Last weekend, I filled up at a KwikTrip in Wisconsin with 91 "recreational vehicle" gas, which contains no ethanol. I was getting 32mpg at 75!! Best ever, and the higher energy density of the gas is the most likely explanation.

One factor not mentioned was climate, where do you live?

 

Another fuel mileage thread...really?

 

I don't know why you guys insist on using sea foam. It doesn't do anything.

 

werd, espeically on our clean engines....

 

Not too much to ask at all.... and you can get much better than 24 hwy.

 

Great explanation, I agree. I too have done this when I first got my car and I do it every few months just to see how my baby is doing... I know exactly how much MPG I am getting on a full tank "driving nicely", when I feel like using that 3.5 for fun... I just don’t care lol

Over all I am getting the same results as "Latito".

I have a 08 TLS.

 

I wouldnt say it doesnt do anything....I mean in terms of helping your gas mileage I would agree...but it does make some pretty sweet smoke come out of your tail pipes!

 

lol aka waste of money i see

 

Ive got the same problem... before I got this car I read reviews of people ranting about mpg in the high 20's and low 30's.... I drove the car from dallas to houston when I first got it (4 hr drive) at about 75 and only got 24mpg keeping the engine just under 2000 rpm. This was found with my own calculations and confirmed by the car computer. Around town I've been getting about 14. The 14 mpg I can understand because I just got the car so I've been a little heavy footed, but the 24 I just dont get. My car has 50K miles. Im going to change my city driving habits and see what that does to my mileage. I got wayyy better mileage with my 6 speed C6 and I didnt drive that car conservatively at all.

EDIT - oh yeah my car has all brand new BFG G-Force Super Sport AS inflated to 34psi... dunno if that makes much of a difference.

 

Driving habits...check your tire pressure also.

 

so no to seafoam? btw how much does an extra 200 lbs do to your mpg, i.e. 2 jl's?

 

the TL is already heavy as is.