4WD Sports Sedans

For the longest time, Sports Sedans were limited to being two-wheel drive. If a car came out as a 4WD, it would need to be converted to either FWD or RWD. In the modern era, all-wheel drive cars are now permitted, but they're not about to wipe out the category like the R32 GT-R "Godzilla" Skyline did to the FIA's Group A formula.

The regulations still allow for a wild Sports Sedans build... or just a nice, fast budget one... but before you build a 4WD Sports Sedan there are a number of key points of difference to know that keep their peak attainable performance under control.

Permitted Vehicle
On top of needing to be an eligible model (in simple terms, most mass-produced sedans, coupes and hatchbacks are), only those that were originally produced as 4WD can be constructed as 4WD Sports Sedans.

Construction
There is an Article in the Sports Sedans rules with sub-articles dealing with car construction. In that there’s a specific sub-article to deal with 4WD cars, prescribing that the construction utilise standard factory sheet metal, the standard engine block configuration, and the standard cylinder head configuration. It goes on to clarify that the standard factory sheet metal needing to be retained is in the areas of roof, pillars, door sills, floor section, and sub-frame assemblies which also captures all the suspension mounting points. The exceptions to any of those parts remaining standard are; modification to the wheel wells to provide clearance for tyre and wheel assemblies, drilling holes for the fitment of permitted accessories and components, and removal of unused standard brackets.

Performance Balance
Under the breakdown of minimum weights, an additional 100kg is added to the minimum based solely on being a 4WD configuration. A popular example would be a 2.0 Litre Turbo with a multi-valve engine, which gets a Motorsport Australia standard multiplication factor of 1.7 on the swept volume for forced induction, taking it to a 3.4 Litre effective capacity. On the “RWD/rear-wheel drive” table that’s a minimum racing weight of 900kg, then from the adjustments table there is 0kg for being multi-valve as it’s under 2.5 Litre swept volume, and add 100kg for being a 4WD, brings it to 900+0+100 = 1000kg minimum racing weight including driver and fluids at any time it gets weighed. A note though, when it comes to the engine rules all Sports Sedans regardless of construction have a maximum power linked to the weight of the vehicle, and in this example if it were sitting on minimum weight then 667hp would be the maximum, while the more overweight it is the more power it is allowed.

Electronics
There is a limit to the electronics and driver aids on clean-sheet spaceframe builds. Meanwhile, there are relaxations to that for all Floor Pan construction vehicles that spaceframes don’t get, and as a 4WD is a Floor Pan construction all of them apply. The key aspect are, it needs to be the OEM component to suit the vehicle, and if it didn’t have it, it can’t be added. The exceptions for Floor Pan cars are Stability Control, Suspension Control, Damper Adjustment, Antilock Braking System, Differential Adjustment Control, Ride Height Control, Rear Wing Adjustment, Automatic Gear Selection, and Clutch Control.

Regulations
We store an archive copy of the rules on the QRDA website in the downloads area, but the ones with regulatory authority are on the Motorsport Australia website where there’s no permalink to point you to ~ so when looking for the current "official regulatory" rule set you have to navigate their “manual” section to find Circuit Racing 3rd Category. The QRDA’s archive copy is however stored here, Group 3D Sports Sedans: Downloads