My mileage went from 20.5 overall to 17.6 overall since i changed tires. I removedthe original Michelins and installed Dunlop sport signatures. Tires can make a huge difference as well as keeping them inflated at the high end of the recomendations.

 

My OEM Michelins on 17 inch wheels got 26 but I have Hankook V12's on 19 inch now and immediately after the change it dropped to 22mpg.

 

thats strange..i would get your car checked out. I get 650km - 700km/tank. I took the RL from Toronto to Pennsylvania last year and I got 880km out of the tank.

 

Tires are a lot when it comes to rolling resistance. Everything that Acura posts is predicated on the tires that come from the factory. When you change brands, that can change your mileage, due to compounds/tread design/inflation pressures/rolling resistance and time of year.

Let me add this in to the conversation (not to hijack the subject) but what oil are you using? If you are using regular motor oil, that can affect your mileage. If you switch over to synthetic, not only will your engine run quieter and cooler, but the coefficient of friction will be lower and your engine will get better mileage. On our '97 I switched over at 75,000 miles to synthetic and my mileage went up 2-3 mpg. (your results may differ).
I run Royal Purple 5-30w in the '06. I usually run Mobil 1 but for this car I decided to step up a notch. This oil is not cheap.

 

strange, seems everywhere outside the octane levels are higher than what is available here! 90 is the top.

 

can driving mostly local street affect the mile range.

 

I will start by saying that RL is not a car to buy if you are going to nitpick around what mileage it gets. But, pls do not feel this is a critique, but rather my own statement.
Now, mileage: I usually get between 20-22mpg, mostly city, rarely hwy - due to pandemic I do not drive anymore as much since I work from home, however, on longer trips my car does get about 25mpg... when I say longer trips that is a longer trip of a couple of thousands of miles. Feels like I have to go 300-400 miles on one tank hwy straight to definitely notice the difference... I highly doubt someone can achieve 28mpg in mixed driving without pulling fuse out and disabling the AWD... but that's just my 2 pennies

 

There are 3 factors involved in gas mileage. First one is the person stepping on the gas. The 2nd is tires, and the 3rd one is the gas you put in the tank.
Let us have a go at the first one. It is your driving habits that will determine your mileage in town or on the highway. Figure 15-18 around town. No sense talking about driving technique here as that is something you have to learn on your own about how hard you push that gas pedal.
The second one is tires. That can make a huge difference in mileage in town or on the road. It is called rolling resistance. How much contact tire is on the road, tire compound and how the tire is constructed. You want a sport tire? Then figure junk gas mileage as that is for spirited driving and soft compound. You want mileage, go with a tire that is 70-80K miles with a AA or AB rating for wear/temperature.
You can put in 89 oct gas and you will get low mileage. Put in 97 oct and expect to get a lot better mileage as it burns different and more miles to the smiles. Try to find gas with the lowest alcohol you can. Some gas stations carry gas with no alcohol. We have one here in central Arizona.
My '06 RL gets about 18 in town and on the highway, with the better gasoline, I can get 25-29. I put it on cruise control and let it roll.

 

You guys are okay.. im having real issues up here in canada. 11mpg city driving .. ive owned a kb1 for 6 years now maybe.. never been this bad..

 

I get the same numbers as you. I'm generally soft on the gas pedal and a bit of a hypermiler.

 

As a conservative driver, my 2005 RL with 243k pampered miles, premium gas, 32F - 30R tire pressure, averages 27 to 29 mpg combined driving, and 32 to 33 interstate.

 

Ummm, no. The fact is, higher octane fuel has fewer energy units by volume than lower octane fuel; said another way, 97 AKI fuel will virtually always deliver lower fuel economy than 87 AKI fuel. The only time a high octane fuel will deliver better fuel economy is if the compression ration and intake boost are both dynamic enough to bring the flame front in the combustion chamber right to the very edge of incipient detonation, and that is definitely not possible in a bone stock 2G RL.

 

I find this hard to believe.

 

I have seen this occasional high mileage when I use Shamrock gasoline that is formulated for high altitude. Beyond that I see the lower numbers quoted of 27-29. The best I have ever seen was 33 mpg.
The post about using lower octane vs the high octane for gas mileage. in my RL shows that I get the lower mileage for the lower cost. I have often wondered if the cost difference is a benefit. A mathematician could figure it out.
That is what has always impressed me was the gas mileage for a car and engine size of the RL.

 

I'm not sure what you're trying to say here, but the fact is, high AKI fuels will uniformly deliver slightly lower fuel economy in a car like the RL compared to lower AKI fuels. This has been scientifically proven over and over and over and is not open for discussion.

 

Try using an additive. I recently poured in 4 oz of Lucas High Mileage Fuel Treatment just to clean out the injectors and clean out over the years of build up in the fuel system.

 

LOL, waste of money, lots of companies would love for you to believe fuel injectors get dirty, but the fact is, with he exception of some sort of a catastrophic supply chain failure, or a fuel system failure in your car, your fuel injectors will stay factory clean for many hundreds of thousands of miles.

 

Perhaps a waste of money for some, but others might disagree with you. I put two of the small bottles of the Lucas injector cleaner through my 1993 GMC pick up that had never had any maintenance on the injectors in 250,000 miles. It was running well. After putting in the first bottle, while driving to work, the injectors started to clean up and I could sense something was happening. The truck ran better and smoother. The next tank got another bottle and it ran like a new truck again. I call it cheap maintenance, What have you got to lose but a few dollars?

 

The same way you claim higher AKI fuel will improve fuel economy; simple explanation, placebo effect.