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Discussion Starter #1
Our gas mileage has been on the decline since we got our Rav 4 Hybrid Limited in May. As you can see from the attached log pic, it has gone from a "best" of almost 40MPG down to around 30MPG.

We were routinely averaging around 35MPG until the last couple of tanks. We thought it might be bad gas, so filled up last time at a different place. It seems to be worse.

Wondering what it could be? We're driving pretty much the same, which is not much. Daily errands and such are only about 5 miles, 20-30 mile trips once every week or two. On a road trip to FL (from TN) in May we got 37.2 for the entire trip (1800 miles).

Wonder if it's AC (it's been hotter than a $2 pistol here), run of bad gas, or what?

Any ideas?

We're about due for our first 5000 mi. service/checkup, I'll be interested to see what they have to say.
 

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Nowhere near enough data to draw any conclusions. Pump the tires up to around 38-40, keep it in ECO mode and limit the A/C as much as possible. At worst the A/C only lowers averages about 1-2 mpg unless you're idling at lights all day.

As a very general rule, expect highest MPG in the spring and fall. Summer should be a little lower and winter the lowest.

Your initial 40mpg was a fluke and probably due more to pump shutoff errors than anything else.
 

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Our gas mileage has been on the decline since we got our Rav 4 Hybrid Limited in May. As you can see from the attached log pic, it has gone from a "best" of almost 40MPG down to around 30MPG.

We were routinely averaging around 35MPG until the last couple of tanks. We thought it might be bad gas, so filled up last time at a different place. It seems to be worse.

Wondering what it could be? We're driving pretty much the same, which is not much. Daily errands and such are only about 5 miles, 20-30 mile trips once every week or two. On a road trip to FL (from TN) in May we got 37.2 for the entire trip (1800 miles).

Wonder if it's AC (it's been hotter than a $2 pistol here), run of bad gas, or what?

Any ideas?

We're about due for our first 5000 mi. service/checkup, I'll be interested to see what they have to say.
Mine has declined as well, but it has been about 2 weeks of 90+ degree weather here and I have been running the AC for the duration of my trips. Today we have a nice toasty 98 degree day and there is no end to the heat until next week. If you are not, I suggest keeping it in ECO mode as suggested.
 

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Discussion Starter #4
We keep it in eco mode all the time, so it's not that. The measurements are all from the computer, which I trust to be pretty accurate, so the comparisons are apples to apples relative.

It just occurred to me that we put the factory cross bars on the roof rack about the time this seemed to have started. Wonder if they could mess up the aerodynics that much? Not that the Rav 4 seems all that aerodynamic to start with. Will take them off and see if it changes anything.

Will check the tire pressure, too. It was 60+ (!) when we took delivery from the dealer. Let it out to the recommended 32psi and that fixed the harsh ride. Mileage was fine, for a while. Will check to make sure they are not underinflated, may try over inflating a bit to see if that helps without messing up the ride.

We drove Prius for ten years and there were variations between seasons, winter gas, etc. but we never noticed this much. And that self trained us on how to drive to maximize fuel efficiency.
 

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We keep it in eco mode all the time, so it's not that. The measurements are all from the computer, which I trust to be pretty accurate, so the comparisons are apples to apples relative.

It just occurred to me that we put the factory cross bars on the roof rack about the time this seemed to have started. Wonder if they could mess up the aerodynics that much? Not that the Rav 4 seems all that aerodynamic to start with. Will take them off and see if it changes anything.

Will check the tire pressure, too. It was 60+ (!) when we took delivery from the dealer. Let it out to the recommended 32psi and that fixed the harsh ride. Mileage was fine, for a while. Will check to make sure they are not underinflated, may try over inflating a bit to see if that helps without messing up the ride.

We drove Prius for ten years and there were variations between seasons, winter gas, etc. but we never noticed this much. And that self trained us on how to drive to maximize fuel efficiency.
In my case all I can think of is running the AC for the entire trips. I do not even run the daytime lights to try and conserve power and it was still lower. The tire pressures are 36, same as our previous gen RAV4. The claim is that the RAV4 is more aerodynamic. Let me know if things change after removing the crossbars.
 

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Discussion Starter #6
Mystery may be partially solved. Tire pressure has gone down to 28.5 for some reason. Was going to replace these tires (Yokohama Geolander) with Michelins anyway, so this is a good excuse.

Also took off the cross bars but haven't been anywhere yet.

I'm guessing its the tire inflation.
 

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I check tire pressure every 2-3 weeks, normal pressure loss is 1-3psi per month, so it doesn't take long to be underinflated.


Tire Deflation: What Causes Tire Pressure Loss?


1. Osmosis of air through the tire casing can lead to a loss of 1 to 3 PSI per month, depending on the specific tire make and model. The type of compounds used in the manufacture of the tire can have a big impact on osmosis. The composition and gauge of the tire innerliner compound also plays a significant role in osmosis. Losing 2 PSI per month does not sound like very much, but after 12 months the tire would be considered “flat” and should be removed from service. If a tire is measured to be 20% under the fleet’s specification, the industry recommendation is to remove the tire from service, dismount and determine exactly what is going on with the tire.
 

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Curious as to what model Michelin your looking at to replace the OEMs. Hope the pressure adjustment fixes your MPH problem.
 

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Discussion Starter #9
@Quickdtoo, thanks. All these years and I didn't realize you need to check tire pressure that often. (Even says so right in the manual.) Guess I always assumed they would check/adjust when I got it serviced. Looks like that's not frequent enough.


@JohnSTL, looking at Michelin Premier A/S. Will report back how we like them.
 

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Mystery may be partially solved. Tire pressure has gone down to 28.5 for some reason. Was going to replace these tires (Yokohama Geolander) with Michelins anyway, so this is a good excuse.

Also took off the cross bars but haven't been anywhere yet.

I'm guessing its the tire inflation.
Interesting I was looking into the Michelin Defenders.

https://www.tirerack.com/tires/tires.jsp?tireMake=Michelin&tireModel=Defender+LTX+M/S&partnum=265HR7DLTX&vehicleSearch=false&fromCompare1=yes

I'm going to wait until these tires need replacing though as the 91AV tires are not so bad so far, but based on the tread life I think thats coming up soon because I drive lots.
 

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@Quickdtoo , thanks. All these years and I didn't realize you need to check tire pressure that often. (Even says so right in the manual.) Guess I always assumed they would check/adjust when I got it serviced. Looks like that's not frequent enough.


@JohnSTL , looking at Michelin Premier A/S. Will report back how we like them.
There's a way to get the TPMS to tell you when they're down a bit.

Pump the tires up to 3 lb over what you want to run. Now reset the TPMS.

Let out 3 lb of pressure. Now when any tire goes 2 lb low it will warn you.

You won't get any better MPG from the Premier tire, but its better in every other way. Handling, noise, traction, its all better.
 

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Tires - Nitrogen air loss study
Consumer Reports News: October 04, 200705:53 PM
Filling tires with nitrogen rather than air is becoming a common practice in the replacement tire market. This service offers tire dealers another avenue for making money while also promoting safety. The claimed safety benefits often include the potential for reducing air loss compared to an air-filled tire. Maintaining proper inflation can help prevent tire overheating; promote optimum tread life; and reduce rubber aging and wheel corrosion. The use of nitrogen in large truck fleets and the commercial tire industry are well documented and support these claims.
The National Highway Traffic Safety Administration (NHTSA) has seen reduced aging of tires filled with nitrogen. Though the data does support that passenger car tires could benefit by all the claims made for nitrogen, tire manufacturers say that they already design tires to perform well with air inflation. And while nitrogen will do no harm, manufacturers say that they don't see the need to use nitrogen, which generally adds $5 or more per tire charge.
Consumer Reports wanted to find out if nitrogen is worth the price, so we purchased a Nitrogen Inflation System and checked out how well the inflation held up over a one year period. We evaluated pairs of 31 tire models of H- and V-speed rated, all-season tires used in our tread wear test from 2006. We filled one tire per model with air and the other with nitrogen. The test was quite simple: fill and set the inflation pressure at room temperature to 30 psi (pounds per square inch); set the tire outdoors for one year; and then recheck the inflation pressure at room temperature after a one year period.
The tires were filled and deflated three times with nitrogen to purge the air out of the tire cavity. We also used an oxygen analyzer to be sure we had 95-percent nitrogen purity in the tire--the claimed purity limit of our nitrogen system, which generates nitrogen gas from ambient air.
The test started on September 20, 2006 and the final measurements were taken on September 20, 2007. The results show nitrogen does reduce pressure loss over time, but the reduction is only a 1.3 psi difference from air-filled tires. The average loss of air-filled tires was just 3.5 psi from the initial 30 pressure setting. Nitrogen-filled tires lost an average of 2.2 psi from the initial 30 psi setting. More important, all tires lost air pressure regardless of the inflation medium, so consumers should check their tires' air pressure routinely. No evaluation was done to assess the aging claim.
Bottom line: Overall, consumers can use nitrogen and might enjoy the slight improvement in air retention provided, but it's not a substitute for regular inflation checks.


Tires - Nitrogen air loss study
 

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Discussion Starter #15
@corsair We have Michelin Defenders on our other car, a 2006 Ford Freestyle. No complaints, but we don't drive it much. They have been on there for three years and have probably less than 5000 miles on them.

(We call it our fishing car. It only has about 35,000 miles on it in 10 years. And a lot of that was a road trip to Denver from TN, and a couple of trips to FL. Once we got our first Prius we didn't drive it much any more.)

@rdgrimes that's a great tip on setting the tire pressure monitor. Going to do that. Wondered why it hadn't complained. Guess it hadn't gone down quite enough to trigger it.

Also, just got back from the tire store with a new set of Michelin Premier A/S 235/55 R18 100V tires inflated to 32/32 per Toyota recommendation. Took a long route home about 50/50 mixed highway/street driving, got 34.2 MPG on the 10 mile trip. Encouraging.

The steering response and handling definitely seem improved. The ride seems a little smoother, and bumps are definitely softer and quieter. Not sure about road noise. We always have the Bluetooth or XM going, so it's hard to tell. I turned off the audio and listened, and there is motor, wind and tire/road noise, hard for me to sort out which is which. Turned the stereo back on and it drowns out the road noise. And you can carry on a normal conversation. Drove over some known rough, noisy pavement and it didn't seem any noisier than before. Like I said, can't tell if it's any better but definitely doesn't seem worse.

But that's only the first 10 miles. Going on a 300-400 mile trip Friday, so I'll have a better idea then.

Thanks to everyone for all the great suggestions and feedback. Will update as more is known.

P.S. I got the tires at our local Discount Tire. They seem to have pretty good sales and service. Had bought from them before. Here's a tip. I asked if they had any kind of trade-in for the almost new (4000 or so miles on them) tires that came on the Rav4. They hemmed and hawed a little (for show?) and the manager was like, "about all I could give you would be $35 per tire," like he thought I might turn that down? I said heck yeah. It brought the price down to $156 per tire. After installation, environmental fees, tax, etc. it was $769.79 out the door ($701.40 before tax). I was expecting more like $900, so I'm a happy camper.
 

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@corsair We have Michelin Defenders on our other car, a 2006 Ford Freestyle. No complaints, but we don't drive it much. They have been on there for three years and have probably less than 5000 miles on them.

(We call it our fishing car. It only has about 35,000 miles on it in 10 years. And a lot of that was a road trip to Denver from TN, and a couple of trips to FL. Once we got our first Prius we didn't drive it much any more.)

@rdgrimes that's a great tip on setting the tire pressure monitor. Going to do that. Wondered why it hadn't complained. Guess it hadn't gone down quite enough to trigger it.

Also, just got back from the tire store with a new set of Michelin Premier A/S 235/55 R18 100V tires inflated to 32/32 per Toyota recommendation. Took a long route home about 50/50 mixed highway/street driving, got 34.2 MPG on the 10 mile trip. Encouraging.

The steering response and handling definitely seem improved. The ride seems a little smoother, and bumps are definitely softer and quieter. Not sure about road noise. We always have the Bluetooth or XM going, so it's hard to tell. I turned off the audio and listened, and there is motor, wind and tire/road noise, hard for me to sort out which is which. Turned the stereo back on and it drowns out the road noise. And you can carry on a normal conversation. Drove over some known rough, noisy pavement and it didn't seem any noisier than before. Like I said, can't tell if it's any better but definitely doesn't seem worse.

But that's only the first 10 miles. Going on a 300-400 mile trip Friday, so I'll have a better idea then.

Thanks to everyone for all the great suggestions and feedback. Will update as more is known.

P.S. I got the tires at our local Discount Tire. They seem to have pretty good sales and service. Had bought from them before. Here's a tip. I asked if they had any kind of trade-in for the almost new (4000 or so miles on them) tires that came on the Rav4. They hemmed and hawed a little (for show?) and the manager was like, "about all I could give you would be $35 per tire," like he thought I might turn that down? I said heck yeah. It brought the price down to $156 per tire. After installation, environmental fees, tax, etc. it was $769.79 out the door ($701.40 before tax). I was expecting more like $900, so I'm a happy camper.
Glad you are happy with your new tires and thanks for sharing. I looked up the tires on Tirerack and came away impressed. They did a very good comparison with other brands. Here is the report.

https://www.tirerack.com/tires/tests/testDisplay.jsp?ttid=188
 

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Discussion Starter #17
Went on the road yesterday instead of today. About 260 miles, about 70% interstate at 70 MPH and about 30% rural, hilly roads. Averaged 35.2 MPG for the trip. I'm good with that.

(We did also remove the crossbars, so not sure how much that or new tires with proper inflation contributed. Will put the crossbars back on next time we need them and see what happens.)

Still too early to tell 100% about the Michelin Premier A/S tires. The road noise doesn't seem better or worse, maybe just different on some surfaces. The ride is good. Handling is great.

The best news is we went through a torrential rain storm and these tires were excellent on wet pavement. No hint of hydroplaning on standing water, handling was sure, braking normal. The tires track true and handle great on dry or wet pavement. I think I like them.
 

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Thanks for all the good tire information - it is appreciated.
 

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We initially had around 31-33mpg in the city when we purchased it back in February. Since the "Texas Heat" starts in May, ever since then, we've been averaging around 27-29mpg.

It seems a little low to me, but maybe the A/C does have a huge effect on the hybrid MPG. My wife makes alot of short 3-5 mile trips daily, runs it in ECO mode all the time and EV mode when possible. She doesn't floor it either.
 

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Have you checked tire air pressure? That was the main cause for the reduced fuel economy for the OP.




I check tire pressure every 2-3 weeks, normal pressure loss is 1-3psi per month, so it doesn't take long to be underinflated.


Tire Deflation: What Causes Tire Pressure Loss?


1. Osmosis of air through the tire casing can lead to a loss of 1 to 3 PSI per month, depending on the specific tire make and model. The type of compounds used in the manufacture of the tire can have a big impact on osmosis. The composition and gauge of the tire innerliner compound also plays a significant role in osmosis. Losing 2 PSI per month does not sound like very much, but after 12 months the tire would be considered “flat” and should be removed from service. If a tire is measured to be 20% under the fleet’s specification, the industry recommendation is to remove the tire from service, dismount and determine exactly what is going on with the tire.
Mystery may be partially solved. Tire pressure has gone down to 28.5 for some reason. Was going to replace these tires (Yokohama Geolander) with Michelins anyway, so this is a good excuse.

Also took off the cross bars but haven't been anywhere yet.

I'm guessing its the tire inflation.
 
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