Actually the RX350 has what's called a center differential lock. This locks power distribution equally between front and rear tailshafts. However the front diff and rear diffs do not have any locking mechanism - so you cannot actually lock all four wheels.

Nonetheless, the CDL in the RX350 will set it apart from the RX450h in terms of offroadability. In other words, the RX350 will be far more offroadable than the RX450h, until suspension travel limits are reached, and a wheel is lifted off the ground.

 

Going back to the RX450h........ I thought you were supposed to turn the traction control off (while in SNOW Mode) if you really wanted to "dig in" to the snow and plow outta there. Is that the consensus or is that the neanderthal way to do this?

 

Traction control OFF will get you going a lot quicker, but it is less civilized (or neanderthal as you put it). I often turn off TC when exiting an unplowed road onto a plowed/salted road. Gets out of the mess more quickly and then quickly get traction on the wet bare road after some sliding and shifting. With TC on, it's much more smooth entry if you have an extra 5 seconds to slowly and calmly make the turn. When all roads are snowy, I leave TC on to keep 100% in control all the time.

 

You should only turn off TC if you are stuck or if crawling in heavy snow

 

Neither car is a wuss. I would feel okay taking my 450h over a rutted dirt road. I would NOT want to climb over big boulders with one wheel spinning in the air, as you see in some Land Rover or Jeep commercials.

The exhaust system on the 450h has, as noted, a heat exchanger to facilitate rapid engine warmup. A factory replacement would be pricey but there are already units shown on eBay for a fraction of new. And if I really wanted to push the car's limits, I could probably get a cover welded on pretty cheaply.

In snow mode a considerable amount of torque goes to the rear axle. Still, nothing like a full-locking mechanism on conventional 4wd off-road vehicles.

 

well........ the rear motor can muster up about 109 lbs ft. so, that's OK, I guess. I'd have a tough time calling it "considerable" given that it's not even close to 50% of total (or peak) system torque, which is an elusive figure that's never really been published.......

source: Lexus published a total rear MG torque figure for the UK market in newton meters.....