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whats your mpg on RX450h?

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Old 05-03-10, 12:09 PM   #16
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Just curious, are you all running in ECO mode, or standard? I've only had my car for 4 days, and averaging about 28 MPG (per the display) so far in ECO mode.
I've switched back and forth and the biggest difference I can see is faster throttle response with ECO off. So it requires a lighter touch to get same economy but if you do, then no mileage difference with it off. And in the winter you can get faster heater response as well with it off.
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Old 05-03-10, 12:57 PM   #17
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I think the manual says something about the airconditioning compressor throttling back more under load when in the ECO mode. We have only had a few days warm enough for the A/C to kick in and then I did not think about testing ECO mode.

In the winter time the engine runs more with ECO off, thus things warm up faster.
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Old 05-03-10, 01:06 PM   #18
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In the winter I don't care about the mileage. Give me heat!
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Old 05-03-10, 01:26 PM   #19
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Originally Posted by wa3cuj View Post
I think the manual says something about the airconditioning compressor throttling back more under load when in the ECO mode. We have only had a few days warm enough for the A/C to kick in and then I did not think about testing ECO mode.

In the winter time the engine runs more with ECO off, thus things warm up faster.
As far as I can tell that applies to the 350 only. The (h) A/C is totally electric and has no power draw from the engine at all. That's a good thing too.
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Old 05-03-10, 02:32 PM   #20
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the 350 doesnt have an eco mode though, it just has an eco indicator.

I too was confused when I learned that the 450h eco mode affected the air conditioner, seeing as how it doesnt depend on the engine. Apparently, it does...
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Old 05-03-10, 03:21 PM   #21
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Even though the A/C is electric it is still a load on the engine. Anything that runs off the alternator, including charging the 12V battery, is a load on the engine. When the compressor kicks in on the A/C the load on the engine must increase to supply the mechanical power to the alternator that in turn powers the compressor. This is much the same as the electric meter on your house speeding up when your A/C at home runs. (That is a good thing ... it keeps my pension check coming!!!!!)

Just about every vehicle I have owned over the past 15 or so years trottled the A/C on heavy acceleration. Some were very noticeable (2001 Saab) to barely perceptible. My guess is that is what happens in the 350.
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Old 05-03-10, 07:31 PM   #22
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Quote:
Originally Posted by wa3cuj View Post
Even though the A/C is electric it is still a load on the engine. Anything that runs off the alternator, including charging the 12V battery, is a load on the engine. When the compressor kicks in on the A/C the load on the engine must increase to supply the mechanical power to the alternator that in turn powers the compressor. This is much the same as the electric meter on your house speeding up when your A/C at home runs. (That is a good thing ... it keeps my pension check coming!!!!!)

Just about every vehicle I have owned over the past 15 or so years trottled the A/C on heavy acceleration. Some were very noticeable (2001 Saab) to barely perceptible. My guess is that is what happens in the 350.
It's so negligible, even if you turned off the system you wouldn't have noticeably better mileage. What eats bat juice more than anything is the cold. Last summer we had this discussion that people couldn't wait till winter so they could get even better mileage. It isn't gonna happen. This is the best time of the year for good mileage in the (h). Everyone here that had one during the winter months experienced a decrease enough to notice. The further north states a lot more. Go back and look at a few of the strings. All the engine families declined due to the cold, it's natural but ours will as well. Down here in GA it wasn't as bad as some up in Iowa or NY for instance but still declined.

The A/C itself runs off the traction batteries, not the generator. Otherwise it (A/C) wouldn't run at all when the ICE wasn't running. The 12v runs things like the computers. And the voltage is so stable, when the compressor cuts on, you'll never feel a loss of power or see the lights dim, even if parked and the ICE isn't running.
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Old 05-04-10, 05:56 AM   #23
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I'm usually in eco mode. If I'm on hilly road that I know doesn't have sharp turns, I sometimes turn cruise control on and glipse at the way it handles keeping the speed relatively constant up and down slopes. It will often go into the power area going uphill and yet it compensates so I still get reasonable MPG. I find it educational and would like to use it to find the "sweet spot".
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Old 05-05-10, 06:25 PM   #24
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"It's so negligible, even if you turned off the system you wouldn't have noticeably better mileage. What eats bat juice more than anything is the cold. Last summer we had this discussion that people couldn't wait till winter so they could get even better mileage. It isn't gonna happen. This is the best time of the year for good mileage in the (h). Everyone here that had one during the winter months experienced a decrease enough to notice. The further north states a lot more. Go back and look at a few of the strings. All the engine families declined due to the cold, it's natural but ours will as well. Down here in GA it wasn't as bad as some up in Iowa or NY for instance but still declined."


Man, I can vouch for this Jim. Gas mileage is MUCH worse in a cold climate in the winter. Here in IA the average gas mileage we were getting in the winter was right around 25 mpg. The colder it is the worse the gas mileage. When it was down around zero degrees outside, the gas mileage would drop down to about 21-22. BTW, we previously owned the RX400h and that was considerably worse on gas mileage in very cold weather than the RX450h. The gas mileage these days with the very comfortable temperatures (60's, 70's, and low 80's) is up to around 29-30 mpg).

I'm sure that folks living in the deep south (FL, south TX, LA, southern AZ, etc.), where it hardly ever gets cold in the winter, probably do not see that much difference in gas mileage between summer and winter.
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Old 05-13-10, 08:03 PM   #25
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Makes one wonder if an engine block heater would be worthwhile.
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Old 05-13-10, 08:29 PM   #26
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isnt the issue here that the engine isnt heating up fast enough so it isnt running efficiently enough and thus the engine has to stay on "longer"?

if this is the case, regular cars should also be getting worse mileage as well though not as bad as the hybrids which depends on the engine turning off to get good mpg. its all relative, at worst, the hybrid just becomes like a regular car and lexus engines are pretty fuel efficient anyways
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Old 05-14-10, 06:19 AM   #27
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That's right and precisely why Toyota's exhaust gas recirculation will be going into more than just hybrid vehicles. However, where you really suffer is taking short trips in winter in the hybrid. By the time the engine heats up you may already be halfway to your destination vs. driving 25, 30, etc. miles with a warm engine that will be more inclined to shutting off when not needed. Supposedly the 450h is much better with the EGR technology, I'd love to compare it against a 400h and I would hope that we will see this tech. go into the GS and LS hybrids.
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Old 05-14-10, 01:33 PM   #28
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Quote:
Originally Posted by SLegacy99 View Post
That's right and precisely why Toyota's exhaust gas recirculation will be going into more than just hybrid vehicles. However, where you really suffer is taking short trips in winter in the hybrid. By the time the engine heats up you may already be halfway to your destination vs. driving 25, 30, etc. miles with a warm engine that will be more inclined to shutting off when not needed. Supposedly the 450h is much better with the EGR technology, I'd love to compare it against a 400h and I would hope that we will see this tech. go into the GS and LS hybrids.
From what I've experienced here in Georgia during the winter and other folks like PatSoxfan in Iowa have remarked during their 'colder ' winter, all cars will get less mileage during the 1st few miles of each start-up in the winter. The 450h has traction batteries under the rear cabin seat and like everything, they get cold too. Until the car is driven far enough for the battery packs to warm into the 60's, then they won't give their full performance for the same period of time w/o requiring juice from the electric motor/generator. Well, it might be full performance as in output, but not as long w/o requiring juice in to replenish. When the electric motor is sending juice to the traction batteries, they are not in turn providing power through the same motor to the drive wheels which means the ICE (internal combustion engine) is doing all the work with no help from the batteries. It might be hard to fathom unless you had one and could watch the 'energy' display. I did experience normal or close to it mileage on longer runs during the winter. And not everyone keeps their car in a garage overnight. That will also make a difference in warm up time.

I'm not a professional but after a night in a Holiday Inn Express, that seems about right
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Old 05-15-10, 05:34 AM   #29
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I've always experienced poorer fuel economy in the winter with all my cars. At one time I was wondering if part of the reason was the colder air being injected into the fuel mixture for ignition.
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Old 05-15-10, 09:35 AM   #30
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Yeah, the temperature of the batteries is an excellent point. I believe it was a topic of controversy in the Fusion hybrid as city mileage could exceed 50 MPG in warm climates, but drop to around 30 in very cold climates. It will be something I am sure will have more of an influence on PHEV and EVs.
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Old 05-15-10, 09:35 AM
 
 
 
 
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