ZAPP Posted April 29, 2008 Share Posted April 29, 2008 This should be enlightening. Lexus claims 17 to 23mpg for the 2001 version of RX300. For awhile my 'info panel' in the car was showing close to 24mpg rolling average.... 23.9, then it began to slip downhill. I used 87 octane for a tank and it hit the skids, then I went back to high test just to see. According to the computer, it has never quite recovered - its currently showing 22.9. But I started wondering if Lexus would build-in a lie, so I have been manually doing the MPG calculation for the past month or so, and I'm showing about 22MPG - maybe 21.8 or so - its hard to know if the idiot-light comes on at the same point each time. From what I have read here and there, I'm getting good MPG. What MPG are you realizing, and have you checked up on your computer to see if its telling the truth? Does anyone know what routine Lexus built in the firmware for arriving at that displayed number?? Also, what's your MPG experience with various grades of gasoline? Quote Link to comment Share on other sites More sharing options...
wwest Posted April 29, 2008 Share Posted April 29, 2008 This should be enlightening.Lexus claims 17 to 23mpg for the 2001 version of RX300. For awhile my 'info panel' in the car was showing close to 24mpg rolling average.... 23.9, then it began to slip downhill. I used 87 octane for a tank and it hit the skids, then I went back to high test just to see. According to the computer, it has never quite recovered - its currently showing 22.9. But I started wondering if Lexus would build-in a lie, so I have been manually doing the MPG calculation for the past month or so, and I'm showing about 22MPG - maybe 21.8 or so - its hard to know if the idiot-light comes on at the same point each time. From what I have read here and there, I'm getting good MPG. What MPG are you realizing, and have you checked up on your computer to see if its telling the truth? Does anyone know what routine Lexus built in the firmware for arriving at that displayed number?? Also, what's your MPG experience with various grades of gasoline? Well, I think I can tell you that the firmware does not have compensation for variations in tire diameter due to wear, pressure variations from temperature or owner "fill" pressure level. That said, I wouldn't think anyone would want to rely on the on board computer for anything other than an approximation of MPG. Quote Link to comment Share on other sites More sharing options...
tmastres Posted April 29, 2008 Share Posted April 29, 2008 I've checked my mileage against the computer a couple of times and found it to be generally accurate. If you're talking 22 on the highway or mostly highway I'd say thats not too far off what I get on the hwy. Generally though I drive mostly in town and get about 18. I ran 89 in mine for a long time then switched to 87 a few years back.I've noticed no difference. Nor did I notice any difference when I ran a couple of tanks of 91. Quote Link to comment Share on other sites More sharing options...
lenore Posted April 29, 2008 Share Posted April 29, 2008 Yea, 17to 18 in town, and 22 on the road... LHowever California GAS sucks, When I go out of state its gets better by a couple of mpg... Quote Link to comment Share on other sites More sharing options...
BBLexus Posted April 30, 2008 Share Posted April 30, 2008 I get about 17 in the city and about 24 on the highway, with about 20 to 21 average - using 87 octane. I would have expected better - even with keeping my tires inflated to 34 psi - coasting, not going above 2800 RPMs. The mileage computer seems to be off by about 5 to 10% - or about 1 to 2 miles. Quote Link to comment Share on other sites More sharing options...
ZAPP Posted April 30, 2008 Author Share Posted April 30, 2008 that tracks with mine I think. I do believe however there is about a 1mpg gain in using super, but doing the math, it does not pay. I am getting my 22 in mixed driving ... that's an average. I do not fun and gun with this car...... I get about 17 in the city and about 24 on the highway, with about 20 to 21 average - using 87 octane. I would have expected better - even with keeping my tires inflated to 34 psi - coasting, not going above 2800 RPMs. The mileage computer seems to be off by about 5 to 10% - or about 1 to 2 miles. Quote Link to comment Share on other sites More sharing options...
screwie Posted May 6, 2008 Share Posted May 6, 2008 that tracks with mine I think.I do believe however there is about a 1mpg gain in using super, but doing the math, it does not pay. I am getting my 22 in mixed driving ... that's an average. I do not fun and gun with this car...... I get about 17 in the city and about 24 on the highway, with about 20 to 21 average - using 87 octane. I would have expected better - even with keeping my tires inflated to 34 psi - coasting, not going above 2800 RPMs. The mileage computer seems to be off by about 5 to 10% - or about 1 to 2 miles. Quote Link to comment Share on other sites More sharing options...
screwie Posted May 6, 2008 Share Posted May 6, 2008 My 99 RX300 with 120K miles shows 30.4 MPG and growing. It started out at about 22 and just keeps getting better the more it's driven. What the ......??? This should be enlightening. Lexus claims 17 to 23mpg for the 2001 version of RX300. For awhile my 'info panel' in the car was showing close to 24mpg rolling average.... 23.9, then it began to slip downhill. I used 87 octane for a tank and it hit the skids, then I went back to high test just to see. According to the computer, it has never quite recovered - its currently showing 22.9. But I started wondering if Lexus would build-in a lie, so I have been manually doing the MPG calculation for the past month or so, and I'm showing about 22MPG - maybe 21.8 or so - its hard to know if the idiot-light comes on at the same point each time. From what I have read here and there, I'm getting good MPG. What MPG are you realizing, and have you checked up on your computer to see if its telling the truth? Does anyone know what routine Lexus built in the firmware for arriving at that displayed number?? Also, what's your MPG experience with various grades of gasoline? Quote Link to comment Share on other sites More sharing options...
tmastres Posted May 7, 2008 Share Posted May 7, 2008 My 99 RX300 with 120K miles shows 30.4 MPG and growing. It started out at about 22 and just keeps getting better the more it's driven. What the ......??? This should be enlightening. Lexus claims 17 to 23mpg for the 2001 version of RX300. For awhile my 'info panel' in the car was showing close to 24mpg rolling average.... 23.9, then it began to slip downhill. I used 87 octane for a tank and it hit the skids, then I went back to high test just to see. According to the computer, it has never quite recovered - its currently showing 22.9. But I started wondering if Lexus would build-in a lie, so I have been manually doing the MPG calculation for the past month or so, and I'm showing about 22MPG - maybe 21.8 or so - its hard to know if the idiot-light comes on at the same point each time. From what I have read here and there, I'm getting good MPG. What MPG are you realizing, and have you checked up on your computer to see if its telling the truth? Does anyone know what routine Lexus built in the firmware for arriving at that displayed number?? Also, what's your MPG experience with various grades of gasoline? Yo, Dude?????? Quote Link to comment Share on other sites More sharing options...
ZAPP Posted May 11, 2008 Author Share Posted May 11, 2008 34 would be a world beater from all I've heard. I'm suspicious that a number like that is truly "computer generated". on my last actual/real calculation, I was getting MAYBE 20mpg, but the computer showed about 22.9.... Quote Link to comment Share on other sites More sharing options...
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