Yurka

Last week and a half i decided to try using lower octane gas to see if there is really no difference as some of you are saying. with 89 Octane gas from BP i am getting around 12 mpg on average, plus or minus a gallon. I decided to put in 87 octane gas from BP. Driving pattern is the same, im doing same routine every single day, college->work->home. I do about 85% in busy Brooklyn/Queens traffic and 15% on the highway every day. w/ 87 octane gas best ive reached is 8.8 mpg and thats on a highway, in the city it gives me 7.1-7.5 maximum... i was driving normal, no Schumacher stuff whatsoever

jfelbab

You pulling a trailer? LOL I wonder if you have a brake pad dragging. That is really low fuel economy. I'd suspect something is not working as designed. Is that MPG value from your computer or measured?

Yurka

That is what it shows on a dashboard menu, it is really bad on 87 octane gas, i put in 89 octane like usual last night, today i have 12.9mpg...

davrober

I have had my rx 350 awd since new 3/18/11. I live in the suburbs and the car has never gotten great mpg when doing local driving but ut was always 16.5-17.5 mpg . Now Im on Long Island, its freezing and roads are crappy . Car is garaged . Last 3 weeks since the 40k service and new Bridgestone 400 tires it has dropped to 12-13.5 mpg . Even highway is a little off. Anyone having this issue . I called service and he started with the tires are different the fuel in winter is aerated, tire pressure might be off. I always use Suncoc 91 octane and if its not available I will use 93 . I am at a loss . I can't believe new tires or winter mix gas or even temps in the 10-20 degree would cause almost a 40% decrease. The service rep said if theres no lights on the panel the engine is fine. He says they didn't do anything to it at the 40k service because its not required at that interval. Has anyone experienced this type of drop. If the car was new Id say thats just it in winter but in 4 winters this is a first for me . Thanks

Yurka

tires might play a role, i had Michelin tires, then someone slashed 2 front tires on my car, so i went over to mexicans and got used tires for like 100$, they were different brand, tread was close to my rear tires so i drove on those for about a month while waiting for sale to get 4 brand new tires, my gas mileage dropped a lot, then i got brand new Michelin and my mileage got up again.

lexus114

in order to get optimum fuel millage, tires must be low rolling resistance. doubt those Bridgestones are..

coachlkg

According to Consumer Reports low rolling resistance tires will save you only 1 or 2 mpg.

jfelbab

New tires usually always come with a drop in fuel economy. New tires can be over a half inch in circumference larger than worn tires. The odometer/computer doesn't know about tire circumference it only know about wheel rotation. Then there is rolling resistance... New tires have about 20% higher rolling resistance than worn tires. Here is a good explanation of why this loss in fuel economy occurs.

http://www.tirerack.com/tires/tirete...jsp?techid=177

lexus114

Um,, thats still a savings. and i wouldnt take to heart what they tell you anyway.

davrober

The Bridgewstones I got are also the factory issue , along with Michelins . Since they are factory OEm they should have been tested when the gas milage rating was determined . I doubt they would cause a 25% reduction in the milage. If they were non standard I would be looking at it as the main issue but they are OEM 's .

coachlkg

So, does that mean the increase in MPG normally experienced during the "break in period" for a new vehicle is primarily due to tire wear?

jfelbab

Perhaps partially but I'd believe most is due to less friction of engine and drive train components perhaps along with the ability of the car's computer management to learn your driving style.

I noticed a marked increase in fuel economy right around 6,000 miles in my 2014 RX. This was relatively sudden and sustained so I wouldn't attribute the increase to gradual tire wear. This increase also came in mid-summer so there was no "winter formulation" gasoline change-over. My prior 2004 RX had increased fuel economy throughout its life.

markneups

I had a 2013 rx350awd that we bought new. The mileage dropped on a regular basis. Never any better than 17. Had enough at 16 and traded in with 13000 miles on the clock. The new 450 h has shown very good mpg right from the start. Increases every day. I only do city driving so the uptick in mpg is slower than if you drove interstate and city combined. Love the new ride with the better mileage.

coachlkg

I have a 2013 RX350 AWD currently at 21,000 miles. I just drove from Indianapolis to St Augustine and back. It did 21.9 MPG for the round trip. Very disappointed in the mileage.

lexus114

wow? that isnt good at all?