EastTnG8r

This car is great and I love it BUT the gas mileage is horrible. I'm getting a consistent 13mpg and am using premium from Exxon Mobil. A friend said to replace the engine air filter and clean the MAF sensor. I haven't done that yet but plan to hopefully this weekend. Any other advice to try to improve the mpg? It's mostly city driving but even on the highway it doesn't seem to improve much/if any at all. Any advice on an air filter or will a cheap one suffice?

Thanks for your help!

MX73

Along with changing the air filter, change the plugs, pcv, clean the throttle body, check the tire pressure. Also, check if there are any stored codes. Maybe a faulty O2 sensor is causing the low mpg.

Htony

Wonder if the car was regularly serviced.

RXGS

iTrader: (2)

Do you live in the city? When I'm exclusively downtown, I get around 15-16 in my 2006 300, but will get up to 26 on the highway. Could also be a dragging caliper? If youre on larger wheels, this could also impact MPG. Mine went down when I went from 18s to 19s

gs350fan

Without knowing the mileage and service history it is hard to say. How old are the plugs? When I got the car I changed plugs, cleaned the TB, MAF sensor. I average 19-20 mixed driving with an egg under my shoe. I got very high 20s once on a long highway trip. This is no prius :lol:. It is a very heavy car with a powerful engine. Getting up to speed uses a lot of fuel.

Beyond that you may have to do some diagnostics (maybe a vacuum or exhaust leak, etc).

Rockauto sells Denso air/cabin filters, wipers, etc. cheap. There are also 5% codes if you search. I believe the OEM wipers are Denso Designer brand.

It is what is in the Lexus box. The owners manual specifies a DENSO Part for the spark plugs, not a Toyota one. They are both one and the same.

EastTnG8r

Will do this soon, and report back. Thanks!

EastTnG8r

Seems to be!

EastTnG8r

I do! The majority is driven a few miles in city. But I live a mile from a highway and travel that route often, too. MPG doesn't seem to change much and sticks right around 13mpg. I have the 18s.

EastTnG8r

The plugs were changed 2 years/25k ago along with water pump and belt. Thank the lord it's not a prius. This is a very fun car and I am pretty heavy on it but I still find 13mpg inexcusable. If I was getting 19mpg mixed I would find that acceptable.

Thanks for the info on Denso.

gs350fan

Do you use the bar graph readout? It updates mileage by the minute.

EastTnG8r

*6 month update*

Gas mileage is still horrible. I was getting 11mpg for several months. I have never gotten above 19 and that was all flat interstate driving at 65mph and still only got 19.1mpg. Insane. I've had the fuel line recall done, which, if anything, feels like it made it 1-2mpg worse. Yesterday I put Shell gas in my car, and maybe it's just my imagination but it seems like the mpg has jumped 1-2 mpg. Still, inexcusable. I had a 5 series BMW with similar engine and HP and it got 2x the mpg this gets. My mom has the Camry sport with the V6 in it and gets 2.5x the MPG I get. Just crazy. I have tried all the tips everyone has suggested. Nothing improves. It gets very expensive putting gas in this thing at 11mpg and premium gas. IDK what else to do. I DO NOT want to get rid of the car, I love this girl. But, I also can't afford 11mpg forever. An independent mechanic said he would spit codes for me but would charge me the cost of labor to do it and it most likely won't give anything since the CEL isn't on.

Any help?

masboy

iTrader: (30)

thats really bad, my 06 gs430 v8 gave me 16mpg city and 21mpg freeway. 13mpg?! might worth to get it scanned, at least you will know if there is any real issue or not.

maybe exhaust leak somewhere?

Htony

Even if CEL is not on, you can scan for store fault. (history). Not even a faint sign(or clue) why the car has so poor mpg?

EastTnG8r

None. Lexus just looked it over...albeit half-assed I'm sure. Don't some auto part stores check for codes for free? I'm kind of annoyed my mechanic was going to charge me full labor cost just to check.

gs350fan

Codes come on when you have exceeded a calibration limit for a certain emission standard. Diagnostic(looking at live data) can show aging and failing components. That being said, a true professional or experienced DIY guy has to look at the numbers.

Advance Auto checks codes, but without a light or recent battery reset you are unlikely to find anything. Codes are also misleading. Parts stores love to read codes because the 16yo kid can tell you to buy an oxygen sensor, and it may fix the problem 50% of the time. Then you come back for more parts. Many "Mechanics" work this way too.

What you need is a good scan tool to look at fuel trims, MAF, etc. And know how to interpet it.

Another thing you can try is a compression and leakdown test. If that passes out, you can be sure the engine is fine and some sensor or loose vac hose is the problem.