jimf

Anyone with any experience of or advice on the type of AWD used on the Toyota Sienna? Not intended for off road use but for reducing the risk of loosing traction on steeper inclines on unploughed/gritted roads.

I understand it's not "true" 4X4?

Oakvillian

depends what you mean by "true" 4x4. The Sienna AWD has a non-locking centre differential and uses the ABS system to isolate a wheel that loses traction. In that respect, it's more of a 4x4 than a number of other part-time systems that only engage the second axle once traction has been lost, but the lack of a limited-slip or locking differential means it's not properly off-road capable.

I wouldn't bother, if it was my choice. One of the main advantages of the Sienna, like the Odyssey/Grand Caravan/Quest or any other minivan, is the versatility of the seating. You sacrifice a lot of that by stuffing a rear axle in the space where the third row of seats would normally stow (when not in use). I'm not that familiar with the Sienna, but I'd bet there's less room in the back of the AWD than of the FWD versions.

Rather than mess around with AWD, take the saving you'd make by buying a 2WD minivan and invest it in a decent set of winter tyres on a spare set of rims. Winter tyres will help you stay away in the first place from situations in which AWD might have been helpful.

iaink

Plus less to go wrong, less weight to drag about, less drive train friction and consequently better fuel efficiency.

jimf

I think the Sienna is full time AWD in that you can't switch it off and as you say uses ABS to isolate a wheel that looses traction. The space taken by the rear wheel drive mechanism doesn't seem to take away any of the interior space but does take space where the spare tyre goes on the FWD models. The result is that the AWD model uses run flat tyres which is the main disadvantage. I expect fuel economy will be poorer as well due to the extra weight and using two drive axles all the time.

It doesn't have much ground clearance so wouldn't be suitable for off road whatever the capability of the drive system.

I've heard the part time systems are poor as it feels like you loose control of the vehicle and then suddenly the other axle kicks in.

I would get winter tyres for any vehicle anyway.

Atlantic Xpat

"full time 4x4" is generally accepted as both axles / all four wheels being driven at once, all the time. Examples would be the subaru range of vehicles plus systems fitted to some jeeps, LandRovers etc. Vehicles such as the Sienna and CRV have 'on demand' AWD/4x4 systems that provide power to all four wheels when neccessary. If you want a Minivan rather than an SUV and feel the need for 4x4 then the Sienna might well fit your bill. Offroader it is not though!

Alan2005

I've got an AWD and I won't be taking it off road. At least not intentionally.

shelley748

I drive a CHevy Venture Ext Van AWD and its great compared to my old Ford Windstar...

bodgerx

The CRV's system is a mechanical hydraulic clutch-based system which basically means that both front and back wheels have to rotate at pretty much the same rate. It's actually quite highly rated in the snow.

calgarylady

What is AWD & FWD. We bought a new sienna ce 6months ago , choose it cos of the space it has inside . With 3 kids I guess thats what we need for now.

ClanickP

Good for room inside. Used one for 2 weeks although it was not the AWD. Would not use or buy one. Pretty rubbish handling around corners etc.

Greenhill

AWD is "All Wheel Drive", where the power from the engine goes to the front wheels. If the front wheels begin to spin, power is then also sent to the rear wheels.

FWD is a marketing con trick.It basically means "Front Wheel Drive" (where the engine power only goes to the front wheels). It's is pretty much the default for cars and entry level SUVs but the vehicle manufacturers like to label them FWD to trick people into thinking the F is for "Four" (or four wheel drive).

There's also...
4x4 or 4WD - where engine power typically goes to all four wheels all the time.

RWD - is common only really for sports cars and some four wheel drive vehicles (for when they're not required to power all four wheels). The R, obviously, means "Rear", where the engine power goes to the rear wheels only. Rear wheel drive vehicles have a reputation for not being very good on icy or snow covered roads.

iaink

I dont know that FWD is a marketing con...they have to call it something dont they?

Given that FWD has the weight of the engine over the driven wheels its no suprise that its more effective in snow / ice than the RWD, but 4x4 / AWD is ultimately going to be better for maintaining forward motion in poor conditions.


Its important to note though that the only thing that will help you stop faster is winter rubber, and AWD etc can give you a false sense of security as to how slippery it really is as the mechanical systems will do a better job of finding any available traction right up to the point that you find that there is not quite enough. In my AWD Subaru you get a feel for how it is moving the power from front to back...that's its way of telling you to slow down... Ignore that at your peril!

Greenhill

Looking at Honda and Hyundai's websites, there's a good example of how it's used (versus how the drive should be specified).

The CRX models have "2WD" specified for the front wheel drive models which, to me, makes it very obvious what the drive type when reviewing the basic specification.

However, looking at the specs of Hyundai's Santa Fe, they list either FWD or AWD with no indication what the "F" is.

Call me a cynic but I'm sure the marketing types at Hyundai chose FWD (in favour "2wd" or "Front wheel drive") for its ambiguity

Greenhill

Great video here which shows the differences between 2wd, AWD and 4WD.


And it's a cute little capable car (I have no idea what it is though )

iaink

You are a cynic

FWD has been used to designate Front drive since long before AWD / 4X4 was a relatively common option. It was initially seen as a negative when compared to "traditional" Rear drive design, and found only in cheap and cheerful econoboxes.

Subaru (and others) has spent a lot of money on advertising to get the average buyer to have any idea what AWD stands for, but most are already pretty clued up about RWD and FWD. The real problem is that the subtle differences between 4x4, AWD, 4WD etc are lost on all but the geakiest engineer types.

Anyway, while we are posting video clips, heres the difference between what appear at a glance to be similar AWD systems...not all AWD is created equal






If you are sticking to the tarmac in canada it doesnt really matter much anyway, all have some benefits beyond 2WD (as long as you are not overconfident as a result), but you would be a fool to spend the money on fancy engineering before you spent it on a decent set of winter tires.