[M!]

there's not much emphasis on how stiff the QP is.
the number reported officially is 3200 Kgm/degree.

"The bodywork's excellent torsional (3200 Kgm/degree 3200kg/° 7000lb/°) and flexural (1300 kg/mm) rigidity translates into even better dynamic handling, more precise suspension and a noticeable reduction in vibration too."

i have a E36/8 M Coupe and it is very very stiff.
while reading the news on the new M Coupe, the rigidity is 32,000Nm/degree:
" the M Coupé platform also boasts a significant functional advantage in terms of chassis stiffness with an unprecedented torsional stiffness of 32,000 Nm per degree, setting a new record in its segment and contributing not only to optimal handling dynamics but an exceptional level of passive safety."

not sure if my math is correct, 3200Kgm/degree = 31,347 Nm/degree.

The QP is a very very stiff Saloon.

(Ferrari 550 Barchetta: Torsional rigidity is 10850lb-ft/degree, and flexional rigidity is 69lbs/inch.
Zonda Roadster = 18,000 Nm/degree

The new carbon fiber central chassis structure features high structural rigidity level: 18.000 Nm/degree in torsional rigidity, 9.000 N/mm in flexional rigidity, for a dry weight of 1280 Kg.)

 

[M!]

other data found online:

Aston Martin DB9 Coupe 27,000 Nm/deg
Aston Martin DB9 Convertible 15,500 Nm/deg
Audi TT Coupe 19,000 Nm/deg
BMW E36 Touring 10,900 Nm/deg
BMW E36 Z3 5,600 Nm/deg
BMW E46 Sedan (w/o folding seats) 18,000 Nm/deg
BMW E46 Sedan (w/folding seats) 13,000 Nm/deg
BMW E46 Wagon (w/folding seats) 14,000 Nm/deg
BMW E46 Coupe (w/folding seats) 12,500 Nm/deg
BMW E46 Convertible 10,500 Nm/deg
Chrysler Crossfire 20,140 Nm/deg
Chrysler Durango 6,800 Nm/deg
Dodge Viper Coupe 7,600 Nm/deg
Ferrari 360 Spider 8,500 Nm/deg
Ford GT40 MkI 17,000 Nm/deg
Ford Mustang 2003 16,000 Nm/deg
Ford Mustang 2005 21,000 Nm/deg
Ford Mustang Convertible (2003) 4,800 Nm/deg
Ford Mustang Convertible (2005) 9,500 Nm/deg
Jaguar X-Type Sedan 22,000 Nm/deg
Jaguar X-Type Estate 16,319 Nm/deg
Lambo Murcielago 20,000 Nm/deg
Lotus Elan 7,900 Nm/deg
Lotus Elan GRP body 8,900 Nm/deg
Lotus Elise 10,000 Nm/deg
Lotus Elise 111s 11,000 Nm/deg
Lotus Esprit SE Turbo 5,850 Nm/deg
McLaren F1 13,500 Nm/deg
Mini (2003) 24,500 Nm/deg
Pagani Zonda C12 S 26,300 Nm/deg
Porsche 911 Turbo (2000) 13,500 Nm/deg
Porsche 959 12,900 Nm/deg
Volvo S60 20,000 Nm/deg

Rolls Royce Phantom: 40,000 Nm/deg
BMW E90: Supposedly 25% higher than E46, look above
BMW Z4: 21Hz... :scratch: Now I just need to figure out how to convert that...
Audi A2: 11900 Nm/deg
Audi A8: 25,000 Nm/deg
Audi TT: 10,000 Nm/deg (22Hz)
Golf V GTI: 25,000 Nm/deg
Chevrolet Cobalt: 28 Hz
Ferrari 360: 1,474 kgm/degree (bending: 1,032 kg/mm)
Ferrari 355: 1,024 kgm/degree (bending: 727 kg/mm)
Ferrari 430: supposedly 20% higher than 360
Renault Sport Spider: 10,000 Nm/degree
Volvo S80: 18,600 Nm/deg
Koenigsegg CC-8: 28,100 Nm/deg
Porsche 911 Turbo 996: 27,000 Nm/deg
Porsche 911 Turbo 996 Convertible: 11,600 Nm/deg
Lotus Elise S2 Exige (2004): 10,500 Nm/deg
Volkswagen Fox: 17,941 Nm/deg
BMW Z4: 14,500 Nm/deg
Ferrari F50: 34,600 Nm/deg
Lambo Gallardo: 23000 Nm/deg
Ford GT: 27,100 Nm/deg
Mazda Rx-8: 30,000 Nm/deg :eyepop: (hard to believe)
Mazda Rx-7: ~15,000 Nm/deg

 

[STARDOC]

Its pretty impressive. It will do 0.87g's on the 600ft lateral skid pad better than the E46 M3. The Maser. coupe will only do 0.85g's, albeit non-lowered.
Can't wait until the 500hp version of the QP.

 

[Avantgarde]

Great find M!

Also found that....
Bugatti Veyron : 60,000 Nm/deg
Porsche 911 Carrera Type 997: 33,000 Nm/deg

It appears to be a close correlation between torsional rigidity and handliing prowess.

 

[M!]

add to the list:
Mercedes SL (MY 2006)
'the torsional rigidity of the car increases from 17,000Nm per degree with the top down to 21,000Nm per degree with the top up."
(i am surprised that the folding tin top actually adds to the rigidity.)

someone in another thread asked about the Spyder being not too stiff.
just don't expect it to be that stiff. i think the shorten wheelbase already helps a little in the feel.
look at the list above and compare the various coupe / convertible:

Aston Martin DB9: 27,000 Nm/deg vs 15,500 Nm/deg
BMW Z4 32,000 Nm/degree vs 14,500 Nm/degree
BMW E46 Coupe (w/folding seats): 12,500 Nm/deg vs 10,500 Nm/deg
Ferrari F360: 14,439 Nm/deg vs 8,500 Nm/deg
Porsche 911 Turbo 996: 27,000 Nm/deg vs 11,600 Nm/deg

most open top cars are less stiff than its fixed roof equivalent.

 

[impex4]

So anyone know the stiffness of the coupe and spyder ?

 

[M!]

So anyone know the stiffness of the coupe and spyder ?

i doubt these numbers are published or release by maserati. nothing to shout about.
i dont think any magazine would strip a car and test the rigidity of a car.

take a guess. look at the ferrari 360, E46, and 996 numbers.

 

[Toffe]

body rigidity

http://en.wikipedia.org/wiki/Body_flex

Body Flex is a lack of rigidity in a motor vehicle's chassis. It is often something to be avoided by car manufacturers as higher levels of body flex is a sign of structural weakness, and means that the vehicle's suspension cannot work as efficiently - the body takes up some of the 'slack', rather than the parts of the car which were specifically designed for this purpose.

Cars of a sporting nature are, therefore, often very 'stiff', while convertibles or cabriolets are not often considered to be good candidates for high-performance sports cars because of their lack of a rigid roof.
Although for some time body flex was a result of attempts to keep a car's weight down, makers such as Audi (the A8), and Jaguar (with the 2003 XJ8) have employed the use of aluminium in chassis production to get around this obstacle, ensuring the weight of these cars and their level of body flex can both be kept to a minimum.

Typically the stiffness of the body is measured in torsion. The body is supported at the spring caps at the rear, and then a torque is applied to the front spring caps via a long beam and a fulcrum. Values achieved range from 1000 ft·lbf per degree for pre War racing cars, up to 25000 ft·lbf per degree for some modern production vehicles.