suckered

No offense, but I think you may need to learn to drive in the snow a little better... 4WD doesn't give you any benefit in the situation you describe. 4WD helps you to get going from a stop and to power through deep snow. Its not going to help you turn or stop, physics takes over. 4WD will not "switch on to correct a slide" and it doesn't "switch on". Its a constant process of detecting wheelspin in the front and engaging the rear wheels to compensate for it. 4WD...FWD...RWD...all the same when you turn and stop. What you are describing happening in your Mercedes is the skid control activating and correcting a slide. Your RX has this feature too, and it works well but it can't compensate for poor tires which many have felt the RX comes with from the factory. Mercedes' yaw correction system may be better...but 4WD isn't your issue here. Thats a RWD biased AWD system with a transfer case though...whole nother animal from the RXh...I would expect it to be better. How do you know that the AWD system was not functioning? You can both see it on the power monitor and feel it when it happens. The rear motor turns yellow and yellow arrows show that power is being supplied to the wheels. This did not happen. Secondly you can feel when 4wd corrects a skid, how it switches in corrects onece or twice and gets you back on the straigthaway again. The Lexus never did. As I wrote, I immediately tried it out in my Mercedes and that worked. However, I no longer have this problem. I put action to words and traded my RX450h in for an Audi Q5 yesterday.

Thanks for the extra info. It is disappointing that the 450h does not do more. I do think that calling it downright dangerous might be a bit of a hyperbole though, as that would mean that every front wheel drive vehicle is also dangerous since they don't engage the rear wheels. Winter tires are the law here, and I'd get them before getting AWD (better handling/safety bang for the buck), at least here where it usually stays close or below freezing for 4 months in a row (el ninio and global warming notwithstanding). We have not been getting much snow here, so I have not had a chance to try doing doughnuts in a mall parking lot yet. I only have had my 450h for almost 2 weeks, and it spent one of those at an airport parking lot. Otherwise, I really love the car. Maybe it is perspective as I came from a 2006 Ford Escape Hybrid. The FEH was a good, dependable car (least trouble than any car I've ever owned, or maybe tied with my '87 Mazda 323LX) but lacked a lot of stuff. AWD, but no stability control. You complain about the Nav system? Have a look at that one! Try flipping CDs when you change regions, or having it plot a drive from anywhere in Canada to anywhere in the US (it can't as it has Canada on one CD, and various US regions on others). Try seat heater buttons that are placed next to the seat position switches (out of sight and no on/off tactile feedback)... You are right. A 2wd car can be driven adequately in the snow. Any car is in itself not dangerous and needs to be driven properly. What is dangerous in my mind is if you expect an advertised safety feature to switch on and it doesn't. Everyone, including Lexus, assumes it does.

Have you tried the 450h and another "more capable" AWD in the same tests? I live in a snowy area and I have not lost control of any car since I was a teenager in my old Scirocco. AWD, stability control and snow tires are not magic. You do have snow tires right? If not, its like buying a fire truck to protect your house but don't spend on a smoke detector... These systems only widen the envelope of control. If you have your family out and driving in the snow, you should be keeping away from the edges anyway. Of course unexpected things happen, and we all want the best control and safety, so I'd be interested in hearing about side-by-side tests with comparably equipped 450h and another "better" machine (BMW X-something?). Yes, my other car is a mercedes 4wd sedan. Both have all weather tyres. I have tried exactly the same thing and the 4wd traction kicks in immediately and straightens the car out. The problem with the Lexus is not the tyres, it's that the RX450h 4wd system does not engage at all if the tyres start sliding. The rear electric motor needs to switch on and it doesn't. There is no manual way of switching it on either.

The RX450h is downright dangerous. The 4 wheel drive does not switch on "on demand" as the advertising says. I live in snowy Massachusetts and do not need permanent 4 wheel drive, but it is essential when the roads are full of snow or ice. I was puzzled at first that the 4 wheel drive only actuated under 25 mph. I tested it on sharp corners in the snow: the back slid out; and on faster, gradual corners: the car side slipped. Never did the 4 wheel drive switch on and correct the slide. I looked in the manual for the method to manually activate 4 wheel drive but couldn't find it. I contacted Lexus. They said that I should use the snow switch. This is a menu item which annoyingly must be switched on every time you drive. It didn't work as it only changes the gear and acceleration characteristics like any other winter/summer switch. They also said that it should work at high speeds when more power is needed. I tried that and found that at 60 mph if I absolutely floored the accelerator on a steep hill the 4 wheel drive would switch on briefly. That's hybrid technology being used to reduce consumption?! I went back to my dealer: what was I doing wrong? They said they'd get back to me. They didn't. I contacted Lexus USA. They had no clue and put me back to the dealer. The dealer promised to pick up the car and test it. After a week of telephone calls they said there was no point in testing the car as it was working "as designed". However it wasn't working as advertised which is that the 4 wheel drive will come on "as needed". I'd say that a broad skid in snow is "as needed". Lexus apparently doesn't, or care. Nobody had ever even tried this feature out despite my frequent requests over many months. They put me onto a "business development" specialist who tried to upsell me on a non-hybrid 4X4 which he said had "a non slip differential" and would therefore have better handling. I am disgusted. Lexus has sold a vehicle on the basis of a safety feature which doesn't work. Relying on it could bring my family (this is my wife's car for ferrying the kids and their friends) into a potentially life threatening situation for them or for other vehicles. All they see it as is a potential new sales opportunity. Hasn't Toyota learned anything from all their recall problems? Don't they care about the safety of their customers? Don't they feel any need to fulfill on their advertising claims? Apparently not. Don't buy this car if you value your life or those of your passengers or others on the road around you, and don't expect any help from Lexus either.