Htony

Also wonder if the vehicle was in snow mode.

riredale

By the way this thread is 5 1/2 years old, doubt anyone who contributed to it then is still around.

Only wanted to mention that my 2010 RX450h does beautifully in slippery conditions and the AWD is essential to going up hills or starting up at a stoplight.

Here in Portland Oregon a few weeks ago we had glare ice for several days. The roads were nearly deserted unless drivers installed chains. But I had great fun in the 450h. Just remember that AWD does nothing for slowing down.

Oh, and "snow mode" is very useful and makes a significant difference. Puts a lot of power to the rear, making it essentially like 4WD.

Htony

In my case, I am trading in '15 RX450h for GX460 for better traction and locking differential. I always use winter tires in winter.

vlad_a

I would be going the same route if the missus approved... it is her DD.
You'll love the GX even more when Toyota kills it along with the 4Runner.

MellonC00

In southern CA, we had frigid temps (for us) this week along with lots and lots of rain. As usual, people were hysterical and driving as if there was a barge navigated by a guy named Noah right behind them. Somehow these people drive faster thinking they will out run the rain....

I gotta say that my cheap tires (heard of Milestar?) have performed OK in handling. But what seems like a 80/20 or 85/15 torque split front to back is somewhat disappointing in the rain. Even under the snow mode, there is much more torque up front. I was at a stand still on a twisty highway due to traffic and saw this car behind me coming at me sideways. I slammed on my gas to lurch, lull, gas again, lurch and lull to go about 5 yards onto the shulder with all that traction control cutting in and out. He missed me by about a foot and hit two other cars in front and to the left of me. this event only took about a second but had me wanting a center differential with 50/50 torque split. This whole electronic VDIM and whatnot is OK on paper but the real operation is quite herky jerky amateurish ballet movement with flat foot.

and We are not even talking about snowy roads. not very confidence inspiring.

vlad_a

If I may recommend Michelin Premier LTX tires? They will help significantly with standstill starting in the wet. They were designed specifically for 4RX.
I got mine tested in an ice storm and then in Florida, where you have to floor it every time to keep away from all the drivers around you.
While the issue at hand will not be solved, the driving experience will be improved.

Htony

Ditto, part of the blame lies with tires. When raining heavy, my most concern is hydroplaning. Never had to worry about traction.
I witnessed air borne car due to hydropllaning on a freeway. Always we depend on Michelin or Continental summer or winter tires. Yes, RX450h is not as good as Acura SH-AWD, Audi Quattro system but it does make enough of a difference.

kitlz

MellonC00, did any lights flash on the dash to indicate VDIM engaged? I can attest to how well it works in snow, black ice and rain. And I have to agree about the tires. There's better brands out there. Still, you were very lucky.

Droid13

Keep in mind that traction control is not the same thing as VDIM but is something that can be used by VDIM (ie its just a page in VDIM's book). VDIM is to keep you from going sideways into the ditch, obviously the guy behind you didn't have it. Traction control is quite ordinary and can activate frequently, you'll see the flashing light on the dash, but when VDIM activates you'll get "fast beep" warning tones while steering and braking systems are nudged by the computer (and TC if needed) to try to prevent a skid.

But I agree with you, it would be nice if the response time on the traction control was faster, but it is what it is on the RXh, the power at the front wheels is always going to be significantly higher. I imagine the ballet as you say is really hard to compute all the variables. At full power if wheel spin is detected, what is the priority, to guarantee control or maximize acceleration? Eliminate spin instantly by cutting power or reducing power perfectly but more slowly to achieve a balance between power and traction, and then how to know when it's ok to ramp up to full power. This type of system would require holding the power at the precise level of a small amount of wheel spin, on the bleeding edge of control. The sensors would have to be much more accurate and the computational power much higher. Definitely the RXh takes a more dumbed down approach, cut power, and then ramp up the power back to full until wheel spin occurs again, rinse and repeat.

I have at times shut off the traction control for a fast exit from side streets without having to worry about TC activating, but it does require the ability to plan more than a second ahead, which probably would do no good in your described situation.

MellonC00

You are right, Droid13, it was the traction light that came on and off. So perhaps it wasn't the entire VDIM that I should blame.

As for the tires, it was the CPO tires that my dealer installed when I bought the darn car. I asked for the LTX (my only RX tires since 15 years ago - I own another RX). I figured it was quite OK but not that great. I'll have to replace these soon.

vlad_a

Technically, TRC is a part of VDIM, so you're not that far off in your assessment.