Rx 300 Gas Mileage (mpg)

[jmcohen23]

Just curious to see if anyone has achieved the 24 MPG on a consistent basis..... I used to drive between 70-80 MPH on the HWY to work everyday, and then one day, I decided to drive around 55 MPH. I have been doing this for about 2 months now, and my gas mileage increased from 18 MPG to as high as 22 MPG. Now, I'm getting about 20-21 MPG. I have 99 RX300 with 105K.

[Free Tibet]

Just curious to see if anyone has achieved the 24 MPG on a consistent basis..... I used to drive between 70-80 MPH on the HWY to work everyday, and then one day, I decided to drive around 55 MPH. I have been doing this for about 2 months now, and my gas mileage increased from 18 MPG to as high as 22 MPG. Now, I'm getting about 20-21 MPG. I have 99 RX300 with 105K.

I have a 2000 RX300 with 87K. I was initially getting 21-22 on the highway and 18 in the city. Our highway miles are mostly in the relatively flat parts of the Carolinas, traveling between Columbia, Raleigh & Charleston and mostly driving 80-85. When I tried driving around 75-80 instead, I noticed I could average 24 on a trip. When I tried driving 65-70, it dropped to 22-23, so I think there's a real torque efficiency in the high 70s. I've also noticed that the effects of drafting on MPG are amazing! Of course, I don't advocate doing it to the point of dangerously tailgating, although I suspect the effects of that would be off the chart. Drafting even 50 feet behind a car of similar or greater size noticeably ratchets up the MPG, although it's not something I've tried to quantify over a long trip. I think Mythbusters said that drafting even at 100 feet at 55mph, you get something like a 10% increase in fuel efficiency.

As for city driving, I live in downtown Columbia, so 90% of our city driving is the worst for MPG: block-by-block. Work, daycare, and just about everywhere we shop & eat are within 2-3 miles, mostly of city blocks. I can only assume that "city" MPG ratings generally account for a higher percentage of suburban driving than our 2-3 trips a month (cities being generally bigger than downtowns). That said, we're currently averaging 17 MPG in the city. When we were driving out to the beltline for daycare 3 days a week, we saw much longer stretches between stoplights and our MPG was a tick higher at 18-19.

All of this is a combination of my mileage-conscious driving and my wife's mileage-irrelevant driving. :) And I keep the tires at 42psi.

[tmastres]

I get around 18-19 in mixed driving of any sort but on the highway I used to be able to get 24.5 if I concentrated. I have a well worn route of 200mi. form here in Santa Barbara to North San Diego county. When I first go the RX I could get the 24.5 to 25 if I kept it below 65, now with about 110k mi on it the best I can do is about 23.5 or so. Most of the time on pure highway driving I get about 22-23 at 70-75mph. Thats because theres just no way you can drive that slow (60-65) on SoCal roads. The min speed is 70 or you end up with people continuously glued to your !Removed! no matter what lane you're in.

I certainly haven't found any "torque efficiency" at driving over 70 (maybe its there but I haven't noticed it) What I do find is more rolling and wind resistance and less mpg.

[dchan865]

Just curious to see if anyone has achieved the 24 MPG on a consistent basis..... I used to drive between 70-80 MPH on the HWY to work everyday, and then one day, I decided to drive around 55 MPH. I have been doing this for about 2 months now, and my gas mileage increased from 18 MPG to as high as 22 MPG. Now, I'm getting about 20-21 MPG. I have 99 RX300 with 105K.

It sounds about right. I've been getting about 21.6 MPG on my RX300, has about 118K miles on it.

[wwest]

Just curious to see if anyone has achieved the 24 MPG on a consistent basis..... I used to drive between 70-80 MPH on the HWY to work everyday, and then one day, I decided to drive around 55 MPH. I have been doing this for about 2 months now, and my gas mileage increased from 18 MPG to as high as 22 MPG. Now, I'm getting about 20-21 MPG. I have 99 RX300 with 105K.

Go to your dealer and have the available C-best options set such that you can disable the A/C cooling system indefinitely, throughout the winter months, by simply switching it off one time via the pushbutton. The second C-best option unlinks the A/C from operating automatically, without any indication, in both full and partial windshield defrost/defog/demist mode.

Then go to Home Depot and purchase a manual water shutoff valve to install in line with the coolant flow to the heater core. Use the valve to turn off the flow throughout the summer months.

Not a substantial improvement in FE but also not inconsequential. And you will have no more instances during the wintertime of sudden unexpected episodes of windshield fogging. No windshield fogging about 5 miles down the road in the early morning nor on a mountain pass when the A/C shuts down due to decloning OAT unbeknowist to you and shortly thereafter the windshield suddenly fogs over.