MPG better when driven hard, Highway Sweetspot
08-13-13, 06:10 AM
#16
...I also increased the PSI in all 4 tires to an uncomfortable level(above 36 psi) in hopes of increasing MPG as well. .02 mpg maybe!
I did recently start to see some MPG gains when I had performed a relearn(removed the ECU-B & EFI Fuses together) and put in some 93 octane. Drove the RX like I stole it for a while. But, although the dash screen showed some imporvements, my overall tankfull of gas(from my handheld calculator reading) was no different overall than what our RX is getting normaly anyway!
My wife accelerates from a standing start, faster than I do (similar to what you folks are talking about) but, her MPG per tank is always less than mine in all of our vehicles.
Also, I have performed the cleaning of the MAF Sensor, IAC Valve, PCV Valve, TB Cleaning.
Last edited by CharBaby; 08-13-13 at 06:20 AM.
08-13-13, 06:48 AM
#17
Lexus Test Driver
Thread Starter
I have infact removed the Roof Rack Cross Bars(for which we've never used) for a whole summer, several years ago in search of some no cost MPG gains. I got nothing! At least, not anything measurable beyond the normal tank to tank fluctuation that I was getting normaly.
I also increased the PSI in all 4 tires to an uncomfortable level(above 36 psi) in hopes of increasing MPG as well. .02 mpg maybe!
I did recently start to see some MPG gains when I had performed a relearn(removed the ECU-B & EFI Fuses together) and put in some 93 octane. Drove the RX like I stole it for a while. But, although the dash screen showed some imporvements, my overall tankfull of gas(from my handheld calculator reading) was no different overall than what our RX is getting normaly anyway!
My wife accelerates from a standing start, faster than I do (similar to what you folks are talking about) but, her MPG per tank is always less than mine in all of our vehicles.
Also, I have performed the cleaning of the MAF Sensor, IAC Valve, PCV Valve, TB Cleaning.
I also increased the PSI in all 4 tires to an uncomfortable level(above 36 psi) in hopes of increasing MPG as well. .02 mpg maybe!
I did recently start to see some MPG gains when I had performed a relearn(removed the ECU-B & EFI Fuses together) and put in some 93 octane. Drove the RX like I stole it for a while. But, although the dash screen showed some imporvements, my overall tankfull of gas(from my handheld calculator reading) was no different overall than what our RX is getting normaly anyway!
My wife accelerates from a standing start, faster than I do (similar to what you folks are talking about) but, her MPG per tank is always less than mine in all of our vehicles.
Also, I have performed the cleaning of the MAF Sensor, IAC Valve, PCV Valve, TB Cleaning.
08-15-13, 06:03 AM
#18
Maybe with the X-Bars removed and the side mirrors pulled inward, there could be some very small benefits in MPG, who knows? Although, I think that some additional front fascia lowering skirt would do the most in this area, to help reduce the air that gets underneath the vehicle, along with some front tire covering that allows the oncoming air to pass around the tires...all from the skirting in the front!
These 1st gen RX's just aren't that aerodynamic! .36 Cd IIRC! But, this is only the drag from oncoming wind. There is no mention of the uplift coming from beneath the vehicle, causing a rise in the whole mass and possibly changing the Cd itself at highway speeds.
In a wind tunnel, the vehicle mass is stationary as to measure how the wind travels around the structure. It's completely different on the highway, especially with SUV's/CUV's where, there isn't enough windforce to push the vehicle downward closer to the road as in a properly designed car with a lower drag coefficient. Thus, creating less uplift from beneath as well
What ch'a think?
Yesterday, I tried accelerating a bit quicker in 1st gear to 2nd in hopes that...the sooner I got to 2nd gear, maybe there would be some mpg improvements.
NO GO! I just watched the MPG reading from the blue screen plummit downward. It was holding at ~20.1 mpg until I started accelerating faster from a dead stop. NOT WOT, just quicker! Slowly, the MPG's went down to ~19.4
So, I changed back to my normal driving habbits and the mpg's began to return upward toward the 20 mpg's while I was driving.
These 1st gen RX's just aren't that aerodynamic! .36 Cd IIRC! But, this is only the drag from oncoming wind. There is no mention of the uplift coming from beneath the vehicle, causing a rise in the whole mass and possibly changing the Cd itself at highway speeds.
In a wind tunnel, the vehicle mass is stationary as to measure how the wind travels around the structure. It's completely different on the highway, especially with SUV's/CUV's where, there isn't enough windforce to push the vehicle downward closer to the road as in a properly designed car with a lower drag coefficient. Thus, creating less uplift from beneath as well
What ch'a think?
Yesterday, I tried accelerating a bit quicker in 1st gear to 2nd in hopes that...the sooner I got to 2nd gear, maybe there would be some mpg improvements.
NO GO! I just watched the MPG reading from the blue screen plummit downward. It was holding at ~20.1 mpg until I started accelerating faster from a dead stop. NOT WOT, just quicker! Slowly, the MPG's went down to ~19.4
So, I changed back to my normal driving habbits and the mpg's began to return upward toward the 20 mpg's while I was driving.
Last edited by CharBaby; 08-15-13 at 06:15 AM. Reason: added info
08-15-13, 08:52 AM
#19
Lexus Test Driver
Thread Starter
Maybe with the X-Bars removed and the side mirrors pulled inward, there could be some very small benefits in MPG, who knows? Although, I think that some additional front fascia lowering skirt would do the most in this area, to help reduce the air that gets underneath the vehicle, along with some front tire covering that allows the oncoming air to pass around the tires...all from the skirting in the front!
These 1st gen RX's just aren't that aerodynamic! .36 Cd IIRC! But, this is only the drag from oncoming wind. There is no mention of the uplift coming from beneath the vehicle, causing a rise in the whole mass and possibly changing the Cd itself at highway speeds.
In a wind tunnel, the vehicle mass is stationary as to measure how the wind travels around the structure. It's completely different on the highway, especially with SUV's/CUV's where, there isn't enough windforce to push the vehicle downward closer to the road as in a properly designed car with a lower drag coefficient. Thus, creating less uplift from beneath as well
What ch'a think?
Yesterday, I tried accelerating a bit quicker in 1st gear to 2nd in hopes that...the sooner I got to 2nd gear, maybe there would be some mpg improvements.
NO GO! I just watched the MPG reading from the blue screen plummit downward. It was holding at ~20.1 mpg until I started accelerating faster from a dead stop. NOT WOT, just quicker! Slowly, the MPG's went down to ~19.4
So, I changed back to my normal driving habbits and the mpg's began to return upward toward the 20 mpg's while I was driving.
These 1st gen RX's just aren't that aerodynamic! .36 Cd IIRC! But, this is only the drag from oncoming wind. There is no mention of the uplift coming from beneath the vehicle, causing a rise in the whole mass and possibly changing the Cd itself at highway speeds.
In a wind tunnel, the vehicle mass is stationary as to measure how the wind travels around the structure. It's completely different on the highway, especially with SUV's/CUV's where, there isn't enough windforce to push the vehicle downward closer to the road as in a properly designed car with a lower drag coefficient. Thus, creating less uplift from beneath as well
What ch'a think?
Yesterday, I tried accelerating a bit quicker in 1st gear to 2nd in hopes that...the sooner I got to 2nd gear, maybe there would be some mpg improvements.
NO GO! I just watched the MPG reading from the blue screen plummit downward. It was holding at ~20.1 mpg until I started accelerating faster from a dead stop. NOT WOT, just quicker! Slowly, the MPG's went down to ~19.4
So, I changed back to my normal driving habbits and the mpg's began to return upward toward the 20 mpg's while I was driving.
Try accelerating harder throughout till you get to your desired speed.
What I have noticed works best is, to get up to speed quickly. Let's say the speed limit is 40 mph, I'll accelerate to that moderately, i.e. 3.5k rpm, maybe 4k. And then apply very, very little throttle to maintain speed. This yields best mpg for me.
10-14-13, 09:08 PM
#20
Driver School Candidate
Hey all,
I've noticed that the few times that I've tried to hypermile, that the MPG isn't as good as driving hard. LOL, yes, I'm serious.
From what I've seen, and it's not scientific at all so don't take my word for it.
IF you get up to speed slowly, like 1.5k rpm and leisurely get up to speed then the mpg isn't that good.
IF you get up to speed quickly, like 3k rpm, maybe more the mpg is good since once you get up to speed you can get off the throttle and only apply light throttle to maintain speed.
I've been able to get 19.8 mpg in the city, by accelerating hard and coasting a lot. If I get up to speed slowly, I end up around 17.8 mpg.
And, If I just accelerate hard, without coasting and keep my foot on the accelerator I end up at 16.7 mpg.
Help me make sense of this. BTW, these numbers are hand calculated.
My question, has any one seen this occur on their RX? i.e. drive hard = better mpg
On other cars', you usually get the best mpg by driving gently. However, that doesn't seem to be the case here.
I do know that the RX will upshift immediately upon letting go of the throttle, so I suspect getting up to speed quickly and then coasting allows it to get into top gear quicker than getting up to speed slowly.
Also, what is your sweetspot on the highway for the RX? I've seen in the past I think, people saying it was 70/75? Is this accurate?
I plan to find out my sweetspot and report back, but I thought it would be nice to have a few datapoints.
I understand the best mpg is going to be with 4th gear and TC locked. Which I think is around 40-45 mph on the RX300.
In case you didn't want to read the entire post, I've put my questions in bold.
Thanks!
I've noticed that the few times that I've tried to hypermile, that the MPG isn't as good as driving hard. LOL, yes, I'm serious.
From what I've seen, and it's not scientific at all so don't take my word for it.
IF you get up to speed slowly, like 1.5k rpm and leisurely get up to speed then the mpg isn't that good.
IF you get up to speed quickly, like 3k rpm, maybe more the mpg is good since once you get up to speed you can get off the throttle and only apply light throttle to maintain speed.
I've been able to get 19.8 mpg in the city, by accelerating hard and coasting a lot. If I get up to speed slowly, I end up around 17.8 mpg.
And, If I just accelerate hard, without coasting and keep my foot on the accelerator I end up at 16.7 mpg.
Help me make sense of this. BTW, these numbers are hand calculated.
My question, has any one seen this occur on their RX? i.e. drive hard = better mpg
On other cars', you usually get the best mpg by driving gently. However, that doesn't seem to be the case here.
I do know that the RX will upshift immediately upon letting go of the throttle, so I suspect getting up to speed quickly and then coasting allows it to get into top gear quicker than getting up to speed slowly.
Also, what is your sweetspot on the highway for the RX? I've seen in the past I think, people saying it was 70/75? Is this accurate?
I plan to find out my sweetspot and report back, but I thought it would be nice to have a few datapoints.
I understand the best mpg is going to be with 4th gear and TC locked. Which I think is around 40-45 mph on the RX300.
In case you didn't want to read the entire post, I've put my questions in bold.
Thanks!
When I accelerate from a stop, I come off the gas petal a little and then back on so I can force shift the transmission to the higher gear early. This seems to give me consistent 21.5 mpg. Other wise normal driving I get 19.5. hypervish I see the same with the mph that you mention.
I bought this Lexus used and never driven one before. So as I been driving this now for 2 years, I still feel that the transmission stays engaged longer than it needs almost makes me feel like its braking, does not coast, slowing the momentum. I end up kicking it out to neutral and it coast longer.
Would be nice to have control of the shift points.
Thread
Thread Starter
Forum
Replies
Last Post
