sightdev

My RX/AWD now has little over 1000 miles but I was really impressed over the weekend when I was driving the RX at 100+mph in heavy rain to get to our out of town hockey game. I don’t think I would have attempted this with any other cars in the past including the 2005 RX we had. Stability and confidence of the 2010 RX was incredible, and not realizing I was traveling at 100+mph, I just couldn’t believe how “sure” footed the RX felt in the rain. I consistently did 80-90 mph for good 20-30 minutes in the open area and it felt as good as it does on dry road. I think I made a good choice with 2010 RX compare to MDX and others I had considered before. I still wish I had HUD and it would have been very useful in foul weather days when full concentration is on the road. Novelty of mouse control Navi is wearing off as the performance/accuracy is same as previous RX and LS.

rxets

18" or 19"? Sport pkg?

Thanks. Just curious.



My 18" regular AWD is running smoothly on the highway or rainy days, too. But I never had the chance of riding it fast on the situation you're experiencing. Good to know it. Who knows if I will have to do it in emergency.

sightdev

Typical packaged RX AWD on starfire; 18’s, premium, Navi, comfort, wood/leather, tow prep and little bits and pieces. Tires make all the differences and I think it’s Bridgestone tire currently come standard are quieter and feel better than the original Michelin that came with 2005 RX. Current RX is mechanically well engineered and because of the combination of tire and insulated wheel well does really good job in isolating road noise.

The G Man

Like I tell my wife, SUVs have a high center of gravity, its not like driving a sedan, you take any SUV over a 100 MPH, you are asking for it. One wrong move and you are upside down. Sure it may seem stable when cruising in high speed, but any emergency maneuver will sending you rolling. So please slow down when driving SUVs, stablity at high speed in a SUV is a false sense of security.

sightdev

You are absolutely correct. Even with all the engineering went into our 2010 RX, three digit travel in any road condition is foolish. Its good that the RX has governor set at 114mph. I grew up in family with SUVs like Surburbans, countless Jeeps since 60’s and recent decade with ML and RX but I was in such hurry that I accelerate without realizing I was doing 100+mph. It would have been nice if I had HUD which is in direct view of the road. I did for sometime on open road but did slow down when traffic started to appear. But it felt more confident in the rain than the A4 Quattro I had long time ago with high performance tires.

rxets

A4 Quattro is full-time AWD sedan, which will ride better in that condition for sure.




IMHO, to me, it's good to know what this car is capable of doing. That's about all. If someone desparately likes to do so, it's on their own. Ppl may be unhappy with this type of talks about high-speed in the car forum. First of all, we don't encourage ppl to try or do it. And, this is just like "seat-belt" thing, everyone knows it's the mandatory stuff, but ppl still try to find the ways to get rid of by any conditions or reasons. Any car forums will always have the threads talking about how to disable buzzer due to...

The G Man

Well, your A4 is older I assume, older tires, suspension and steering components. When all things are equal, the quattro AWD system is hard to beat. When the RX is doing highway speed, its only in FWD mode until it detects wheel slip. Two different kind of AWD between the two cars.

sightdev

Actually I remember seeing a video clip from Lexus about how the 2010 RX AWD works based on vehicle/road condition and speed. In normal casual driving it can run at 100% FWD mode until slippage or highway speed is achieved, In highway speed, AWD will be active but varies in percent ratio distribution as condition changes. This may explain why AWD and FWD both rated at 18 city but 24 Hwy for AWD and 25 Hwy for FWD.

Another note, original Bridgestone tire that comes with 18’s are rated at the bottom of list in Tirerack’s users rating chart. I guess most OEM tires are of low quality but I was disappointed considering how much I liked it to date. I guess I will be looking for tires after second oil change.

The G Man

I found this one a website:

http://lexushelp.com/models/2010/rx/

It seems like at steady speed, the new RX is FWD only until it detects slipping in the front wheel, then it will send torque to the back wheels. Its the same system they use on the RAV4.

Lexus again offers its RX 350 and RX 450h crossover models with a choice between front-wheel drive and all-wheel drive. The RX 350 introduces an all-new electronically controlled Active Torque Control AWD system. As in the previous RX 400h, the RX 450h hybrid uses a separate rear electric motor-generator to provide power to the rear wheels when road conditions or throttle response dictates.

The previous RX 350 model’s AWD system used a viscous coupling locking center differential to provide 50:50 torque distribution. In the 2010 RX 350, Active Torque Control AWD uses an electronically controlled coupling ahead of the rear differential to vary torque distribution anywhere from 100:0 to 50:50 front to rear, depending on driving dynamics and road conditions. The new AWD system is 35 lbs. lighter than the previous system and reduces parasitic losses by 30 percent.

When accelerating, or starting off on a low-grip surface, torque is quickly provided to all four wheels. At steady speeds, torque is sent only to the front wheels, enhancing fuel efficiency.

For handling agility and control, the AWD system increases rear-wheel torque when the vehicle’s front tires start to lose traction and decreases rear-wheel torque when the vehicle’s rear tires start to lose traction. On rough or sandy terrain, an AWD LOCK switch provides enhanced traction performance for low-speed maneuvering (if in LOCK mode, the system reverts to AUTO mode when speed exceeds 25 mph). To help prevent a tight corner-braking condition (shuddering) during low-speed cornering, the system reduces rear wheel torque.

rxets

Dunno if RX10 physically shifts power to the rear wheels continuously in the good road conditions (straight and plain). I would think this RX is acting as FWD in most of time.

I read a few articles similar to The G Man posted above. It’s hard to believe RX will make this “Active Torque Control AWD” doing AWD stuff most of time. I strongly believe RX10 will ONLY shift power to the rear when the car desperately needs. In most of conditions, RX AWD should do the minimum or do nothing. IMO.

Infiniti Intelligent AWD seems to do a little more actions and continuingly shift power to the front “more” than Lexus Active Torque Control AWD.

Btw, Toyota even doesn’t feel necessary to public or market the details of their Active Torque Control AWD. You probably won't hear from Toyota saying how good it works the way it's been disigned to or how intelligent it is during the driving. Well, this Active Torque Control AWD is just the FWD with the ability of transferring the power to other 2 wheels. The way to market this system is to make up this pretty name to tell you it’s the wonderful system.

The G Man

In the old days, these so called electronic AWD system didn’t work as well as the permanent mechanical system. When the electronics system detects slips and send power to the rear wheel, you lose at least a second or 2 right there. We all know when you are doing 75 MPH, a lot can happen in one second. The Toyota / Lexus Active Torque Control system is suppose to send power to the rear wheel when accelerating from a stop, that’s when there is a good chance of slippage. Also, it is suppose to anticipate slipping condition and apply power to the rear. I have no idea how the computer anticipates adverse conditions, but I do know the system works very well in the RAV4. These electronic AWD are not meant for off road use, they are design for on road driving in the snow or rain where 95% of the SUV AWD system gets use. Although these electronic AWD are still not as good as the real thing, they are getting real close in functionality.

rxets

Perhaps, I shouldn't wake up this thread again. But, I just want to say: I got the good experience today during the pouring rain in New England areas.

EXCEPT driving thru the puddles on the shouders, the car is running smoothly. (Generally I feel the permanent-AWD vehicles are moving better than RX. )



* When RX engaged with AWD and moved in the rain, MPG was decreasing 10~30%. AWD and rain friction may be the factors.

sightdev

It could also be false sense of security because 10RX does so well with isolation. I have been driving hard and it does really well going in-out of the ramp and in the rain. Annoyance time to time when vehicle “hunts” for right gear when accelerating after coasting/slowing. Sometimes it pauses noticeably before shifting to lower gear. Really annoying and can be dangerous. Mileage also went up a little from 19.5 to 20.5-6 so I guess things will loosen up little more and will improve as it puts on more miles. In NE, nobody drives speed limit and I am always doing 80+mph just to maintain flow of traffic so when I average 20+ with A/C and full load, IMO, it is good.

rxets

As long as I don't drive over the water puddles, everything is almost perfect.

I dare not speed 65+ in NY/NJ/CT. But I do enjoy 75 ~ 85 in MA, ME, etc, maybe because I can find more ppl doing the same in these areas, and I don't like to move alone on the highways. I really have to say this car is moving strongly and smoothly in varied high speeds.



Caution: speeding can be harmful to ppl and yourself...