Rx400h: Awd Vs. Fwd?

[clean energy fan]

My wife and I are looking to get a new RX400H, and I'd appreciate people's opinions on whether to get the AWD or FWD version.

Best as I could tell the AWD has slightly better acceleration, but the FWD gets slightly better mileage. Anyone know if the AWD make a significant difference for driving in snow, ice, and rain??

[Jim Clark]

My wife and I are looking to get a new RX400H, and I'd appreciate people's opinions on whether to get the AWD or FWD version.

Best as I could tell the AWD has slightly better acceleration, but the FWD gets slightly better mileage. Anyone know if the AWD make a significant difference for driving in snow, ice, and rain??

To cal the 400h AWD is a joke. The only thing driving the rear wheels is the rear electric motor. I've hear of situations where people have been on snow or ice and the system goes nuts and basically shuts down to prevent damaging the hybrid system.

That being said, I wouldn't buy one without AWD, it'll be important when you sell it.

Do a search on AWD.

[ilovelexus2007]

My wife and I are looking to get a new RX400H, and I'd appreciate people's opinions on whether to get the AWD or FWD version.

Best as I could tell the AWD has slightly better acceleration, but the FWD gets slightly better mileage. Anyone know if the AWD make a significant difference for driving in snow, ice, and rain??

I got an AWD, where I live in MN, the AWD helps BIG TIME when driving in the snow and ice. If you live in location where you don't see snow or ice, I think you can get a FWD to save a $1000 plus 1 to 2 mile MPG. But most SUVs these days have AWD (Murano, MDX, FX45 etc...), if you can afford a Lexus, I don't think the price different between AWD/FWD matters, just go with an AWD because it is MUCH BETTER driving.

[wwest]

My wife and I are looking to get a new RX400H, and I'd appreciate people's opinions on whether to get the AWD or FWD version.

Best as I could tell the AWD has slightly better acceleration, but the FWD gets slightly better mileage. Anyone know if the AWD make a significant difference for driving in snow, ice, and rain??

When I travel to the Boston area during the winter months I am careful to NEVER rent a FWD vehicle, far too dangerous in my opinion. Were I purchasing an SUV in this "class" for your area my first choice would be the RDX (for SH-AWD), second would be the X3. IMMHO the AWD RX400h would be a much better choice than the standard AWD RX. Most of the stories of the RX basically "shutting" down involve the Traction Control system used to implement AWD functionality on the non-hybrid RX. The latest RX has the ability to turn TC off for that very reason.

[s10]

FWD is perfectly fine in most situations. The AWD on snow can help, but not necessarily. On snow it is the weight of the car that is the biggest handicap when going downhill or when sliding.

I managed to slide in the Italian Dolomites with my previous RX 330 AWD with chains on the front and going 5 mph.

Actually in the Dolomites you see many similar cars, especially the Cayenne, that crash because the drivers think they're safe because of the AWD.

I just got a RX400H AWD, only because of the color really, if they would have had a FWD I would have taken that one for that extra 1 mpg (slightly lighter car)

So, if you like to feel more secure, get an AWD, but don't rely to much on it!

[wwest]

FWD is perfectly fine in most situations. The AWD on snow can help, but not necessarily. On snow it is the weight of the car that is the biggest handicap when going downhill or when sliding.

I managed to slide in the Italian Dolomites with my previous RX 330 AWD with chains on the front and going 5 mph.

Yes, FWD is already quite dangerous on the slippery stuff and then adding even more traction at the front raises the "bar", increases the danger, just as it states in your owners manual.

Actually in the Dolomites you see many similar cars, especially the Cayenne, that crash because the drivers think they're safe because of the AWD.

I just got a RX400H AWD, only because of the color really, if they would have had a FWD I would have taken that one for that extra 1 mpg (slightly lighter car)

So, if you like to feel more secure, get an AWD, but don't rely to much on it!

My '01 AWD RX300 has wheel spacers added all around so as to provide enough wheel/suspension clearance at the rear for the use of tire chains there, first, and the fronts only if needed

[SOMEONE ELSE'S GOT MY NAME]

My '01 AWD RX300 has wheel spacers added all around so as to provide enough wheel/suspension clearance at the rear for the use of tire chains there, first, and the fronts only if needed

Wow, who knew? So w/o spacers, there's no room for chains? We run studs in Montana (front & rear). I never though that the stock clearance would not allow for chains. Cables too?

[wwest]

My '01 AWD RX300 has wheel spacers added all around so as to provide enough wheel/suspension clearance at the rear for the use of tire chains there, first, and the fronts only if needed

Wow, who knew? So w/o spacers, there's no room for chains? We run studs in Montana (front & rear). I never though that the stock clearance would not allow for chains. Cables too?

According to your owners manual no chains or cables at the rear.

Reach under and try to slide your hand between the tire tread surface and the bottom of spring mount.

Sienna and HL are the same way.

[SOMEONE ELSE'S GOT MY NAME]

According to your owners manual no chains or cables at the rear.

Reach under and try to slide your hand between the tire tread surface and the bottom of spring mount.

Sienna and HL are the same way.

Hmm. I think it's member 'rxrey' who posted pics here ... with his oversized tires (maybe 1" taller) on his 400h. I'd have wrogly guessed it would have been possible, based on that. Go figure

[s10]

I managed to slide in the Italian Dolomites with my previous RX 330 AWD with chains on the front and going 5 mph.

Yes, FWD is already quite dangerous on the slippery stuff and then adding even more traction at the front raises the "bar", increases the danger, just as it states in your owners manual.

This is new for me, never heard of it. I don't have my manual from that euro car, but pretty sure it mentioned to mount only chains on the front or on all 4 wheels, never just on the back. From all the mountain people I know and who have 4x4's, (most don't) they all mount chains or spikes only on the front wheels, the wheels that steer the car need the most traction, especially going down hill.

UPDATE: I just read the manual of my Rx400H.. it indicates to "have your vehicle fitted with four snow tires or purchase a set of tire chains for the FRONT tires".

and then again, on page 183, which size chains to install: " INSTALL THE CHAINS ON THE FRONT TIRES.

And again on page 184: INSTALL THE CHAINS ON THE FRONT TIRES ONLY. DO NOT INSTALL TIRE CHAINS ON THE REAR TIRES.

[s10]

My '01 AWD RX300 has wheel spacers added all around so as to provide enough wheel/suspension clearance at the rear for the use of tire chains there, first, and the fronts only if needed

Really? did you get bigger wheels? It wasn't needed on mine at all, I used Spiders on the 18'

[wwest]

I managed to slide in the Italian Dolomites with my previous RX 330 AWD with chains on the front and going 5 mph.

Yes, FWD is already quite dangerous on the slippery stuff and then adding even more traction at the front raises the "bar", increases the danger, just as it states in your owners manual.

This is new for me, never heard of it. I don't have my manual from that euro car, but pretty sure it mentioned to mount only chains on the front or on all 4 wheels, never just on the back. From all the mountain people I know and who have 4x4's, (most don't) they all mount chains or spikes only on the front wheels, the wheels that steer the car ned the most traction, especially going down hill.

There is NO tire shop that will install tire studs on only the front of a FWD car, the liability due to the additional potential for an accident due to loss of directional control is far to great. Just think of a tractor/trailer rig going downhill on a slippery roadbed with only tractor/"front" brakes. And no reasonably experienced 4Wd/4X4 owner would EVER install tire chains on the front first. The rule is to put them on the rear first and then add the fronts if conditions warrant.

I suppose if you only want to PULL/drive uphill then desparately heavier traction on the front might work okay.

But yes, for FWD or F/AWD you often have no choice but to mount tire chains first, and often only, on the front.

But keep in mind, CONSTANTLY, that the resulting potential for loss of directional control is so severe as to often be EXTREMELY HAZARDOUS, especially on a slippery downhill drive, and even moreso on a curving slippery downhill drive. And be prepared to QUICKLY shift your automatic transmission into neutral should engine compression braking on the front wheels begin threatening loss of directional control. And remember that ABS cannot be as effective, and may even become completely non-functional, if the roadbed is slippery enough and/or a significant level of engine compression braking is also "in play".

[s10]

I managed to slide in the Italian Dolomites with my previous RX 330 AWD with chains on the front and going 5 mph.

Yes, FWD is already quite dangerous on the slippery stuff and then adding even more traction at the front raises the "bar", increases the danger, just as it states in your owners manual.

This is new for me, never heard of it. I don't have my manual from that euro car, but pretty sure it mentioned to mount only chains on the front or on all 4 wheels, never just on the back. From all the mountain people I know and who have 4x4's, (most don't) they all mount chains or spikes only on the front wheels, the wheels that steer the car ned the most traction, especially going down hill.

There is NO tire shop that will install tire studs on only the front of a FWD car, the liability due to the additional potential for an accident due to loss of directional control is far to great. Just think of a tractor/trailer rig going downhill on a slippery roadbed with only tractor/"front" brakes. And no reasonably experienced 4Wd/4X4 owner would EVER install tire chains on the front first. The rule is to put them on the rear first and then add the fronts if conditions warrant.

I suppose if you only want to PULL/drive uphill then desparately heavier traction on the front might work okay.

But yes, for FWD or F/AWD you often have no choice but to mount tire chains first, and often only, on the front.

But keep in mind, CONSTANTLY, that the resulting potential for loss of directional control is so severe as to often be EXTREMELY HAZARDOUS, especially on a slippery downhill drive, and even moreso on a curving slippery downhill drive. And be prepared to QUICKLY shift your automatic transmission into neutral should engine compression braking on the front wheels begin threatening loss of directional control. And remember that ABS cannot be as effective, and may even become completely non-functional, if the roadbed is slippery enough and/or a significant level of engine compression braking is also "in play".

I think you might be mistaking permanent 4x4 and AWD, RWD and FWD, Winter tires and Studs.

There is absolutely no point installing tire studs on the rear wheels of a FWD.

And you also mix up down hill and uphill; it is uphill you would need more grip on the back, and downhill more on the front.

The most grip has to be where the most weight is and that changes going up/down hill. Since you don't wants to change your chains all the time from the front or the back.. nor taking off/ putting chains on all 4 wheels... and since going downhill has the highest risk of something going wrong, again because of the weight, it makes the most sense using chains/spikes only on the front.

Just like everybody does in the Swiss Alps, where I've lived for 15 years.

[wwest]

I managed to slide in the Italian Dolomites with my previous RX 330 AWD with chains on the front and going 5 mph.

Yes, FWD is already quite dangerous on the slippery stuff and then adding even more traction at the front raises the "bar", increases the danger, just as it states in your owners manual.

This is new for me, never heard of it. I don't have my manual from that euro car, but pretty sure it mentioned to mount only chains on the front or on all 4 wheels, never just on the back. From all the mountain people I know and who have 4x4's, (most don't) they all mount chains or spikes only on the front wheels, the wheels that steer the car ned the most traction, especially going down hill.

There is NO tire shop that will install tire studs on only the front of a FWD car, the liability due to the additional potential for an accident due to loss of directional control is far to great. Just think of a tractor/trailer rig going downhill on a slippery roadbed with only tractor/"front" brakes. And no reasonably experienced 4Wd/4X4 owner would EVER install tire chains on the front first. The rule is to put them on the rear first and then add the fronts if conditions warrant.

I suppose if you only want to PULL/drive uphill then desparately heavier traction on the front might work okay.

But yes, for FWD or F/AWD you often have no choice but to mount tire chains first, and often only, on the front.

But keep in mind, CONSTANTLY, that the resulting potential for loss of directional control is so severe as to often be EXTREMELY HAZARDOUS, especially on a slippery downhill drive, and even moreso on a curving slippery downhill drive. And be prepared to QUICKLY shift your automatic transmission into neutral should engine compression braking on the front wheels begin threatening loss of directional control. And remember that ABS cannot be as effective, and may even become completely non-functional, if the roadbed is slippery enough and/or a significant level of engine compression braking is also "in play".

I think you might be mistaking permanent 4x4 and AWD, RWD and FWD, Winter tires and Studs.

There is absolutely no point installing tire studs on the rear wheels of a FWD.

And you also mix up down hill and uphill; it is uphill you would need more grip on the back, and downhill more on the front.

The most grip has to be where the most weight is and that changes going up/down hill. Since you don't wants to change your chains all the time from the front or the back.. nor taking off/ putting chains on all 4 wheels... and since going downhill has the highest risk of something going wrong, again because of the weight, it makes the most sense using chains/spikes only on the front.

Just like everybody does in the Swiss Alps, where I've lived for 15 years.

What...WHAT...???!!!

I'd like to think you're pulling our legs just a tiny bit but I afraid, sorely afraid, not.

"There is absolutely no point installing tire studs on the rear wheels of a FWD..."

You not only need roadbed traction, traction on a "slippery" roadbed, for acceleration/driving uphill but also for slowing and stopping, and the "dynamics" of the vehicle under acceleration vs slowing or stopping must be seriously considered.

Going downhill on a slippery roadbed with studs only on the front and having to stop quickly.....??

Either your ABS will activate at a VERY inordinate, HIGH, rate at the front preventing you from stopping in the short distance otherwise possible, or the low-traction at the rear end will result in the rear leading the front down the hill.

Personally I would rather have chains or studs ONLY on the rear of a FWD car than ONLY on the front. Yes, that combination would likely never get me moving forward on an uphill slippery roadbed but then moving would eventually mean stopping or slowing and that's where the danger of desparate F/R traction would arise.

Back in my days in MT in the wintertime I remember often using the E-brake lightly going downhill on a VERY slippery roadbed. The E-brake not only helped to keep the vehicle speed lower but also helped to keep the vehicle in line with the direction of travel.

If what you say really does apply to the public in general remind me to stay clear of the Alps during the winter months.

And by our definition in the US there is no such thing as a permenant 4X4 vehicle for road-going use.

On the other hand here in the US "permanent" AWD versions abound, a virtual myriad of those. But the ones with sideways mounted engines are to be ignored, mostly. The only possible, reasonable, exception IMMHO would be an SH-AWD equipped vehicle.

[JeffDonnelly]

AWD for me

[LXPearl]

The key issue on safety for tires and chains is control of the vehicle, not simply whether the vehicle can go up or down the hill faster or better. The ability to stop and steer at the point of losing traction are critical - this it the issue that many 4x4 drivers forget when gleefully driving like crazy in the snow or ice. Recent recommendations on tire placement on vehicles has been overwhelming that the best tires need to go on the rear of the vehicle. Tests of FWD vehicles with the best tires on the front have resulted in sudden and severe (very unlikely recovery) when the car loses control - e.g. braking on ice. It is easier to recover when the front loses control rather than the rear, regardless of FWD or RWD.

Years ago when FWD was relatively new, people primarily thought about the traction issue. It was noticed that once traction was lost on FWD it was difficult to recover or control it. It is only recently that I started seeing a change in practice based on improved recovery when the best tires were on the back wheels - even on FWD. The current recommendation is to assure that your best tires (also chains) are on the rear to enhance your ability to recover if you lose traction.

On FWD, I would go with chains on all 4 tires for safety. For the RX AWD, chains just on the rear may work OK because slippage up front will transfer power to the back. Too bad Lexus does not provide space for chains on the rear tires - that would be a problem if chains are needed. Thankfully, the AWD does quite well without the need for chains in most winter conditions.

[Gryphon]

Personally I would have preferred the AWD for the increased towing capability and performance, but they were scarce when I bought my RX.

Tom