Last post on Mar 15, 2012 at 9:02 PM
You are in the Lexus RX 300/330/350
What is this discussion about?
Lexus RX 300, Lexus RX 330, Lexus RX 350, Toyota Highlander, Car Comparisons, SUV
#49 of 58 Re: Lexus RX350 v. Toyota HIghlander Limited (both 2012) [whichone2012]
Feb 11, 2012 (9:26 pm)
we did a brief test drive of both. we diced to go with the highlander because of the softer ride . however we liked the rx but the ride appeared to be a little stiff.?!??
#50 of 58 Re: Lexus RX350 v. Toyota HIghlander Limited (both 2012) [nosdivad]
by Stever@Edmunds HOST
Feb 12, 2012 (6:31 am)
Tire pressures in new cars are overinflated for shipping and sometimes dealers forget to air them down to spec when they prep them for the lot, making for a bouncy test drive. You may want to try another one.
Either way, a longer test drive is a good idea before buying.
#52 of 58 Performance
Mar 13, 2012 (3:51 pm)
I'm a long time 4Runner owner but am thinking of switching to a Highlander. Haven't driven one yet, but have been doing a lot of research. I'm confused by the different descriptions of it's performance in the Edminds ratings and the Edmunds review. The Edmunds rating says with the 3.5 V6, it "has only enough power to allow for adequate acceleration". That kind of turned me off, but then I read the Edmunds review. There the Highlander with the 3.5 V6 "has especially brisk acceleration". Guess I'll take Edmunds ratings and reviews with a grain of salt from now on. What do owners think about it's performance with the V6?
#53 of 58 Re: Performance [mgrody]
Mar 15, 2012 (8:56 am)
Going from a RWD "based" AWD/4WD/4X4 4runner to a FWD based F/awd vehicle might be fraught with peril unless you truly understand, KNOW, the tradeoffs.
And I do NOT mean the availability of a mostly useless 4X4 mode.
Both of the vehicles you mention are primarily FWD vehicles with only PART-TIME. AUTOMATIC PART-TIME "awd" systems.
I would suggest you consider the base Porsche Cayenne, R/awd, instead, especially if you are in an area of harsh wintertime road conditions.
Decidedly more safe than ANY F/awd system, inclusive of even the best of the best, the SH-AWD system.
#54 of 58 Re: Performance [wwest]
Mar 15, 2012 (10:19 am)
I don't know about the RX350, but the Highlander uses 3 open differentials (front, center, and rear). So it is not primarily FWD with only "AUTOMATIC PART-TIME "awd" systems". As long as traction/friction is equal on all four wheels, power is sent to all four wheels equally, hence "full-time" awd. But as you know with open diffs, power always wants to go to the wheel with less resistance (i.e. traction). This is true regardless if the vehicle is f/awd or r/awd if there are open diffs involved. Hence the use of electronic traction control (i.e. applying brake pressure to the slipping wheel to increase resistance, thus sending power else where).
The notion that r/awd are better than f/awd is false. Without traction aids, any type of awd system (regardless if its fwd based or rwd based) with three open different are really one-wheel drive. A f/awd vehicle with traction aids (e.g. diff lockers, limited slip diff, etc.) will perform better than a r/awd with open differentials.
#55 of 58 Re: Performance [titancrew]
Mar 15, 2012 (2:09 pm)
You are NOT incorrect, clearly...
"..As long as traction/friction is equal..."
But just since when is that of any real matter with the wintertime adverse roadbed conditions for which many (most?) of us purchase AWD systems...?
It's when traction is NOT equal, or so extremely low that EQUAL matters not, that the need for a TRUE AWD system, a R/awd, arises.
"..power always wants to go to the wheel with less resistance.."
Yes, and that results, directly, in the engine output torque level dropping to ZILCH.
TC braking, the method used to re-apportion engine torque to wheels other than the one(s) having lost traction will only be, can ONLY be AUTOMATICALLY activated AFTER, POST the initial wheelspin/slip event.
Should that initial wheelspin/slip event happen to occur at the front (a F/awd virtual CERTAINTY IMO) then the driver, at this instant in time, has lost directional control of the vehicle. Obviously that would not be the case with a rear biased, R/awd, system.
"..The notion that R/awd are better than F/awd is false.."
Modern day R/awd systems automatically reduce or completely CUT engine torque to the front drive at times of expected need to dedicate more front traction coefficienct for the use of lateral control. Those times are pretty much restricted to turning or correction of direction if the need arises.
Modern day F/awd systems operate in the inverse of that. Under low speed acceleration engine torque is automatically re-apportioned to the rear in to make optimal/best use of ALL available roadbed traction. On the other hand, if turning, turning tightly, or accelerating into a turn, F/awd systems will attempt to more heavily BIAS the engine torque to the rear in order to allot more roadbed traction to the front for lateral control, maintaining directional control of the vehicle.
With F/awd, make the turn a tad too tight, or accelerate a bit too hard into a turn, and VSC will activate pre-emptively. VSC will activate since absent doing so the system has predicted a HIGH probability of not enough front traction being available to support the maneuver the driver wishes. The result will be FULL engine dethrottling. To regain control over the throttle the accelerator pedal must first be fully released.
With an otherwise equivalent R/awd vehicle and in the same above circumstance the front traction coefficient WOULD BE, in the worse case, TOTALLY dedicated to maintaining or asserting directional control. Should the system judge, compute, that to much lateral force is required at the rear for the current maneuver, and the driver does not quickly react on their own via cranking in the appropriate level of counter-steering, the same result would occur. The engine would instantly be fully dethrottled.
Oh, and finally, is there a F/awd system manufacturer, even inclusive of the SH-AWD system, that does not advise that the system is FRONT TORQUE BIASED...??
#56 of 58 Re: Performance [titancrew]
Mar 15, 2012 (2:03 pm)
In the past 10 years or so Lexus factory representatives have attempted to explain to me on numerous ocassions, phone and face to face, just how and why the RX and HL series have front torque biasing, most definitely so.
All I have ever gotten out of those explanations is that it has something to do with the mechanics of the center diff'l vs the front diff'l vs the rear diff'l configuration. Number of side, spider, gears in each..?
#57 of 58 Re: Performance [wwest]
Mar 15, 2012 (5:17 pm)
That's very interesting and I hadn't given it any thought. Thank you!
#58 of 58 Re: Performance [wwest]
Mar 15, 2012 (9:02 pm)
"Should that initial wheelspin/slip event happen to occur at the front (a F/awd virtual CERTAINTY IMO) then the driver, at this instant in time, has lost directional control of the vehicle. Obviously that would not be the case with a rear biased, R/awd, system. "
The same thing would occur with a R/awd system too because if the wheel spin occurs a the front, power will be routed to the slipping wheel unless you have an active (i.e. Torsen or equivalent) center diff because power will ALWAYS go to the wheel of least resistance (i.e. slipping wheel). If the F/awd system has an active center diff, it will send the power to rear wheel this situation just like the R/awd. Even your explanation for the different awd system concede this. So I don't know how you can conclude that a R/awd system is better.
Hence, it doesn't matter whether you have a F/awd or R/awd system, it all depends on the type of front, center, and rear differentials. If they are all open, then you have a essentially one-wheel drive vehicle. Very few car-based vehicles come with Torsen center diff or locking/limited slip front and rear diffs anymore. Most use TC ABS to simulate resistance/friction.
Here's an interesting article on why FWD and AWD system based on FWD are better than RWD and AWD system based on RWD in low speed low traction situation.