dxr

reset the avg mpg just as I pulled off the highway. wife will be surprised next time she takes out the RX lol

gotin

I prefer not to reveal my location for now, but I will do later for sure. I am posting a picture of my yesterday's fuel consumption screen. On 20 of February I updated the fuel consumption for every drive. The first bar is for my children's school route with cold car in the morning. On 21 of February (Today on the screen) I drove the children with the RX400h for comparison. You can also see the consumption in Snow mode, described in my previous post. "Yesterday I achieved 6.2 liters/per 100 km (around 38 MPG) for two short drives, 15 minutes each, 2 hours in-between."
Today it is Saturday and the car spent the whole day in the garage, no new data.

I hope, you will get inspired to try the Snow mode.

Aptosuser

I drove the RX in snow mode two miles from our health club to our house today. The car was also still in eco mode. I was not in snow mode going to the club, going mostly downhill, but through a number of dips and rises, That wasn't my intent, because I thought I'd put the car in snow mode while I was still in the driveway, but I'd selected it in the accessory mode before actually powering up the car, which I guess was the wrong way to do it. When I arrived at the club, I was only averaging 19 mpg for the short drive, which was disappointing. I was monitoring the NAV energy display on the way there. I'd expected to see the car relying more on both electric motors but I didn't see any difference. I still didn't understand that the car wasn't really in snow mode on that leg of the trip. On the return trip, after I'd driven a block or so, I decided to take the car out of snow mode. But instead the "hybrid snow" light came on (it wasn't on before) and I realized I'd finally put the car in snow mode. This time the car used both electric motors most of the way and was either running off of or charging the battery much of the way. I was averaging 19.2 mpg by the time I got home, despite the fact that the return trip is mostly uphill. In other words, I picked up mileage on the reverse, uphill return trip while in snow mode. So that was a pretty good demonstration that keeping the car in snow mode is advantageous around our neighborhood, where the speed limit is 25 mph.

But I'm still wondering: What happens when you drive the car at highway speeds. Do you have to turn off the snow mode or does the car cancel it out when you're going 45-65 mph (or faster)?

gotin

I suppose that Snow mode is pretty useless on the highways, I never used it on highways and I really see no point in using it by higher speeds.
Snow mode is automatically deactivated ONLY if the “ENGINE START STOP” switch is turned off after driving in snow mode. This is why I believe that it is totally harmless, because you can switch it ON and drive for hours with any speeds and the computer will not switch it OFF.

The Hybrid vehicles are least effective when you drive with constant speed on an even highway. The more speed acceleration and deceleration, the more fuel efficiency you will get. Hybrids are mostly fuel effective by city driving with a lot of acceleration and deceleration, start-and-go driving with a lot of traffic lights stops. This is my type of city driving since I live close to the city center and I use only roads with 30 to 50 mph speed limits with many traffic lights on my way. I suggest trying Snow mode in such a case only.

bring

My '13 can't be in Eco mode and snow mode at the same time, so I'm guessing you weren't in snow mode.

I do find it fascinating that "forcing on" the rear axle electric motor results in better mileage. I am going to try it.

Do the '14s have snow mode?

gotin

I suppose that European vehicles are more flexible.

My RX450h has no problem to be in ECO, Snow and EV mode at the same time!
Snow mode is not allowed in Sport mode which is pretty logical but it is available in ECO and Normal mode (Normal = both ECO and Sport are OFF).
To be fully precise:
Sport mode cancels Eco and Snow mode if either or both are ON.
Eco and Snow are not allowed when Sport mode ON.

bring

Nope - my bad - I must have been in sport mode and switched over to snow (only had it a week) and assumed switching between all of them switched off the prior.

So question: what does Eco and Snow give you that only Snow does not?

gotin

I suppose that Eco+Snow gives you Snow+optimized air conditioning.
"To encourage a more efficient driving style, the RX 450h features an ECO mode that optimizes the air conditioning’s system and regulates the throttle response for more efficient acceleration."
"A SNOW mode slows accelerator-pedal response to help reduce the possibility of wheel spin."

The purpose of ECO is fuel economy, the purpose of Snow is reduced possibility of wheel spin, but both use the same method - they change the gas pedal response!
Eco gives you fuel economy and I suppose Snow will give you a little bit more fuel economy because the effect of Snow mode on the gas-pedal response is more noticeable. This is the simple logic behind my proposition to test the fuel consumption in Snow mode.

Let's make some tests and share the results.

bring

I thought snow activated full-time AWD?

Aptosuser

Actually, that's where mine has been most effective. The best mileage I've gotten has been driving between here and Southern California (Orange County), when I've topped 30 mpg. I figure if I can get that on the highways, I ought to be able to get more in stop and go urban driving, but I have yet to see that. Maybe this snow mode tactic will prove helpful in that department.

Again, I haven't had a lot of luck driving with eco mode only in those kinds of situations. Slow and go has usually given me better mileage than stop and go. With only eco mode on, I find that it's difficult to keep from using the ICE when getting going again after a full stop.

websailor

This snow-mode discussion is really interesting! Something to give a try since a lot of our mileage is city driving, not very long distances, and a mix of slight uphills and downhills.

On a different note, since Cflutist first started posting, we've been improving our mpg - thanks to this board! We were initially getting about 18-19 mpg. Over the past week, we've gotten it up to 24 mpg in our brand new 450h. I've learned a lot about how to drive it, so I think this will be improving more.

THANK You All!!!!

Aptosuser

I think that despite what the manual says, snow mode does more than change the gas pedal. I've read that AWD in the RX 450h relies on the rear electric motor to power the rear axle in snow mode. That being the case, it stands to reason that when you put the car in snow mode, the rear electric motor will engage more. More electric power should translate into less reliance on power from the ICE. My trip home on snow mode this morning seemed to confirm that, or at least my car's NAV energy screen showing where the power was coming from did. I'm guessing that when you really use snow mode in snow, the car probably relies on the gas engine more, as maybe more power is needed in that case. Plus, if you're using snow mode in snow, you would also no doubt have the heat on, which definitely requires the gas engine to keep running.

(On chilly mornings around here, by the way -- and we're talking at worst high 30s, but more likely low 40s -- I rely on the seat heater which works off the battery rather than the auto climate control with its reliance on the ICE.)

gotin

First
Lets compare the city/highway performance specifications of RX 450h AWD - 30/28 mpg and RX 350 AWD - 18/24 mpg.
By city driving - 30/18 = 1.67 - Hybrid gives you incredible 67% more mileage !
By highway driving - 28/24 = 1.17 - Hybrid gives you moderate 17% more mileage !
By motorway driving, if Lexus would be so kind to give us fuel consumption data, we will definitely get only very few percent better mileage with the RX450h.

Conclusion:
1. The faster you drive, the less effective is the Lexus Hybrid Synergy Drive.
2. The more "start-go-stop" or "accelerate-decelerate" driving, the more efficient is the HSD.
3. HSD is least efficient when you drive with constant high speed on a motorway.

Second
You must know how the city/highway performance specifications are achieved in order to judge you personal results and make comparison.

"The "city" program is designed to replicate an urban rush-hour driving experience in which the vehicle is started with the engine cold and is driven in stop-and-go traffic with frequent idling. The car or truck is driven for 11 miles and makes 23 stops over the course of 31 minutes, with an average speed of 20 mph and a top speed of 56 mph. The "highway" program, on the other hand, is created to emulate rural and interstate freeway driving with a warmed-up engine, making no stops (both of which ensure maximum fuel economy). The vehicle is driven for 10 miles over a period of 12.5 minutes with an average speed of 48 mph and a top speed of 60 mph. Both fuel economy tests are performed with the vehicle's air conditioning and other accessories turned off."
http://auto.howstuffworks.com/fuel-e...explained1.htm

Both specifications are really very appropriate for Lexus HSD, but often our real driving is different.

By certain circumstances I achieve even better then the stated fuel consumption and by other circumstances I achieve much worse results, but always I am fully aware why is that happening. Please note also the highway test specifications. If you make an usual 30 minutes trip, starting with cold engine, driving with cruise control set to 60 mph and your air conditioning is ON, you will definitely get worse results then the official data.

My proposal for trying the Snow mode is for those of you who are close enough to the EPA Fuel-Economy City Testing specifications in their everyday driving.

gotin

You are absolutely right.
I used the simplified Lexus statement for easier understanding.

Let's go deeper.
I could not find any official detailed explanation of RX450h different Drive modes. Here is my best guess based on my general knowledge.
The HSD computer receives:
1. Driver input (gas pedal, gearshift, drive mode, TRAC OFF switch, air conditioning controls, etc) from all driver controllable "switches".
2. All vehicles's sensor readings.
and based on all that data and internal algorithms:
1. "The HYBRID SYNERGY DRIVE computer oversees operation of the entire system, determining which engine/MG should be running, or if both should be in use, or shutting off the internal combustion engine when the electric motor is sufficient to provide the power."
1. The HSD computer is also controlling the electronic Continuously Variable Transmission and the Driving assist systems.

In Snow mode I believe that HSD computer is interpreting differently the gas-pedal input by:
1. Using different algorithm for power distribution between ICE and electric motors.
2. Using different algorithm for selecting appropriate CVT gear ratio, especially by vehicle start and low speed. Only a few Lexus software engineers know what is happening by higher speeds.

Wheel spin is most likely to occur by start or low speed. The slower the speed, the bigger the difference between driving in Snow mode On or OFF and with speed increase, I believe this difference is becoming minimal.

I also believe, that as a side effect, the Snow mode gives you better fuel consumption with the loss of some vehicle's dynamics (slower acceleration), which is not a problem at all.

I feel driving in Snow mode like driving in stronger ECO PLUS mode.

bring

Gotin - is your 450h FWD or AWD?