I have a new 2014 TL Special Edition with about 2500 miles on it. I have been getting 21-22 mpg in the city. Recently I refilled my gas tank and used 89 octane gasoline. I noticed that my mpg dropped to 16-18 mpg. I assumed this was because the engine adjusted timing to compensate for the lower octane. However, when I filled up again with 93 octane my mpg remained in the 16-18 range in city. I've ran several tanks of gas through the car since, all 93 octane, but my mpg is stuck at 16-18 mpg. Combine this with the cost of premium gas and the mpg drop is pretty costly. Any suggestions as to the cause of my mpg reduction? What mpg are you guys getting in the city? How about on the highway? Thanks in advance for any answers!

 

disconnect your car battery, wait 2 mins and reconnect.

let the car recalibrate everything. see if that works out.

how is your driving style? is this a awd? auto or stick? what is your city and highway driving percentage like?

i drive 70% fwy and i get 22mpg on a 2010 auto fwd. you should do better on a 6speed.

 

city and highway % dont mean jack chit.

the car comes with an Average Mile Per Hour read out.
use this number with your average MPG read out because they correlate to each other.

 

^+1 This

 

good info, although i dont see how it relates to what the OP is asking..

local and fwy does affect mpg tremendously... im sure you know that.. and sitting in traffic also hurts mpg.. which also hurts the Average MPH read out that you state.

so again, op what is your driving style.


btw, since your car is new, mpg does get better overtime. i know mine started at 19mpg but after, it slowly climbed up to 22-23mpg

 

lol, but if we both drive 30% city, and you have a different MPG than me....

the MPH doesnt lie.
the MPH will tell you if you're sitting in traffic more, etc.

so it is relevant.
we need both pieces of information, MPG and MPH to see if there is a problem.

as stated, a low average MPH will correlate with a LOW MPG!

and if you're getting 21-22mpg, that's not 70% freeway, son.
unless you're driving 80mph which will decrease your MPG.

average MPH is IMPORTANT.

 

I have a 2 wheel drive automatic with the 3.5 L engine. I'll have to get back to you with the avg. mph, I'd guess I'm driving more than 50% city miles. Most of my time is spent off the freeway with hardly any idling time. Not much traffic in Little Rock usually. I'm not the most mpg friendly kind of driver, but I'm trying! Watching the mpg readout as I accelerate really encourages a lighter foot! Whatever my mix of city/highway driving is, I know something has changed because I'm driving exactly the same mix of city/highway miles and the same routes as I was when I was getting 21-22 mpg in the first 1500 or so miles I put on my car. If anything, I would expect the mph would have improved as the car got broken in a little. I'll try disconnecting the battery and will get back with you guys with my avg. mph after I burn another tank of gas, which won't take long if my mpg doesn't improve! Thanks!

 

reset the battery, if you havent already
then reset the readout.
it doesnt have to be on the next tank, the computer is smart.

then do your daily routine and tell us the MPG and MPH in a couple of days.