unibody vs truck on frame design

[bnz2bimmer]

With so many manufracturers switching over to unibody, I wonder if some of the 'truck-like' studyiness and high center of gravity and commanding driving position, will be replaced, with a more car like ride, which is essentially buying a car..

the reason i ask is that the new suvs e.g. Audi Q5 are essentially an a4, with higher center of gravity , and drives and rides like one.

[jimsaq]

?
even the E53 was monocoque

[FSETH]

I don't see much downside to this besides maybe reduced towing or payload capacity.

Why wouldn't you want a safer, better handling ride with the high, commanding driving position in an SUV?

Body on frame design is a thing of the past as far as SUV's are concerned, IMO.

[JCL]

I don't think manufacturers are switching over to unibody designs, really. What they are doing is offering SUVs that come from two distinct points of origin. Those that come from trucks (Suburbans, Expeditions, etc) are truck-like. Those that come from cars (X5, ML, etc) are car-like. There are more car-sourced SUVs available now, but most of them are more like cross-overs, about halfway to being an SUV, than actual SUVs. There are in fact so many cross-overs that the lines are pretty much blurred. The X6 is a hybrid of an SUV and a coupe, according to BMW. The BMW Gran Turismo is another hybrid design.

[Fraser]

Originally Posted by JCL

Those that come from cars (X5, ML, etc) are car-like.

First generation ML was body-on-chassis. Second gen ML is monocoque.

[LeMansX5]

Originally Posted by Fraser

First generation ML was body-on-chassis. Second gen ML is monocoque.

2nd is unibody and MB admitted that they made a mistake with 1st gen ML when they came out with 2nd gen ML. 1st gen ML drives like a big truck.

[FSETH]

Originally Posted by LeMansX5

2nd is unibody and MB admitted that they made a mistake with 1st gen ML when they came out with 2nd gen ML. 1st gen ML drives like a big truck.

Right. The first gen ML was a body on frame design and it drove like a truck with no where near the car like handling of the e53. I don't think the average SUV buyer wants their vehicle to drive like a truck. There are a few of the largest SUV's that are still based on body on frame design, but some have switched to a unibody design (like the ML) and all the new models introduced for the most part seem to be unibody design. I don't forsee many manufacturers developing new body on frame SUV's in the future. The main reason SUV's like the suburban, Expedition and so on are still body on frame is due to cost because they share their frame with the larger pick-ups from the same company.

On a side note, I read somewhere that the Mercedes GL, which is a car based unibody design, can tow as much as the truck based Yukon. This shows that larger car based SUV's can be successfull. Unfortunately Ford and GM are behind the times and will keep churning out old technology as long as it sells. Maybe with the way gas prices have been in the past and with what is going on in the auto industry, there will be more incentive for Ford and GM to redesign thier larger SUV's. Who wouldn't want a better handling, lighter, safer SUV if it can tow and haul as much as an old body on frame design?

I definitely think the trend is going from body on frame to unibody across the board. Even the Explorer is going to change to a unibody design.

http://www.autoweek.com/apps/pbcs.dl...603954184/1065

[bnz2bimmer]

Cayenne was a body on frame design, but the 2nd generation it is confirmed to be a unibody, another bites the dust

I actually LIked the 1st gen ML , I owned one for 5 years

[FSETH]

I am pretty sure the Cayenne was never a body on frame design.

I am curious as to what you think is better about an SUV that drives and rides like a truck instead of one that drives and rides like a car? What is the benefit?

My friend had a first generation AMG ML55 and he even said that the handling and feel were no where near my e53. If you can tow about the same and haul just as much, why do you prefer your vehicles to drive truck-like? Just wondering.

[JCL]

Agree, the Cayenne was a unibody from the introduction. Same unibody as the VW.

The truck-like sturdiness is an image, not reality, unless you are looking for places to attach racks, winches, etc, or you want the frame for repairability after off-road excursions. The lack of a separate frame on an X5 really only matters to most owners when they want to attach a hitch.

The high centre of gravity is a negative for any vehicle, truck or car. It impairs handling, and reduces stability.

The high driving position is not connected in any way to whether the vehicle has a unibody or a separate body on frame. It does tend to require a higher vehicle, but those can be built any way the manufacturer chooses.