Group A Racing Challenge (Homologation and Racing) [Race Car Evaluation]


In 1984 the german touring car championchip switched to a Group A based rule set and started the greatest era of german national motorracing. What later became DTM started as DPM (German Productioncar Championship), a name that shows the spirit of the competition. These cars symbolized the meaning of “Drive on Sunday, buy on Monday”. Only limited changes were allowed between the production car and the race car, no major reengineering mostly tuning. Aside from the interior race cars and production cars looked mostly identical. To get a feeling, what these cars looked like:

This competition is not meant to have super expensive, technologically ahead of its time super sport cars, these are basically normal cars, tuned to racing spec, people with “some spare money” could buy.


This challenge will be held in two stages. In stage one participants design a production car to please the sporty crowd in Hetvesia, Fruinia and Gasmea. The car will be submitted and to be assigned a Cost and SVC factor based on their normalized desirability compared to the other participants. Once the Factor is set every participant designs a race car.

Naming conventions: Model/Family: GARC - [your forum name]
Trim/Variant: [whatever you want][P or R]
P… Production Car
R… Race Car

  • Tech Pool: 40M P / 55M R
  • No negative quality
  • Submissions of the car file via DM
  • One advertisement required
Production Car
  • Model year not older 1975, Trim year 1985 same for engines
  • Car body not younger than Model year, not older than 1965
  • No carbon panels or chassis
  • Only Clutched and Helical LSD
  • No Advanced or On-Demand AWD
    Seats: at least 4 (2/+2 is fine)
    Engine: free choice of engine layout and size for NA
    Max. 2500ccm for Turbocharged Engines
    free choice of Turbo Geometry and Bearings, but only Waste Gate allowed

Fuel type is free on production car, but make sure its available, as fuel availability affects desirability. If your production car runs the unleaded 100 RON from the Race Car it will have 0 desirability due to 0% fuel availability in 1985.

Brakes: no carbon ceramic brakes
Steering: is free, but electric and variable hydraulic must be changed to manual R&P on the race car
Fixtures: Its not a design contest. Car must be road legal. Head and taillights, indicators, mirrors, windscreen wipers, fuel cap. One front splitter, one spoiler one wing are allowed.

Production cars will be evaluated by the desirability and affordability value of Sport, Family Sport Premium and Fun Premium market segments of Gasmea, Hetvesia and Fruinia in the market mode of the statistics section. (Make sure your production car is the only trim, to get the values. You will have to manually input the estimated cost from Detail Stats mode as the sales price.)

Normalized Desirability = FunP(DxAx0,4)+FamSpP(DxAx0,3)+Sp(DxAx0,3)
Car with the highest normalized desirability gets 100% of permissible est. cost and SVC for the racecar. All others get a percentage related to their result relatively to the best reached desirability in the competition. (Better selling car means more money for the race department.) Lower limit for the budget will be 75%.
Min normalized desirablity 25% of the best car. (If not your cars are considered commercially too unsuccessful to financially support a racing program.)

Race Car

Max Cost: $35000*(Personal Percentage), but no less than $26.250
Max SVC: $5000*(Personal Percentage), but no less than $4.000$

For most engine capacity related tables, a turbo factor of 1.7 will apply. (For example a 1400ccm engine with turbo will be categorized in the 2001-2500ccm class.)
Quality sliders are allowed to differ from production car. (Locked sections must not be unlocked, quality for chassis and engine family must be set on the production car.)

Minimum Weight: up to 1000ccm - 720kg
1000 - 1400ccm - 760kg
1401 – 1600ccm - 850kg
1601 – 2000ccm - 930kg
2001 – 2500ccm - 1030kg
2501 – 3000ccm - 1110kg
3001 – 3500ccm - 1200kg
3501 – 4000ccm - 1280kg
4001 – 4500ccm - 1370kg
4501 - 5000ccm - 1470kg
5001 – 5500ccm - 1560kg
Over 5500ccm - 1650kg

Allowed changes to the engine and car:

**Bottom end:**
  • Bore may be increased by 0.6mm
  • Pistons free to be changed
  • Harmonic dampers and balance shafts can be changed in weight

Top End:

  • Compression Ratio free to be changed
  • Turbo engines may not exceed a compression ratio of 11.5:1
  • Camshafts timing can be changed (VVT and VVL cannot be added or removed, but VVL RPM slider can be changed)
  •    Spring Stiffness and Rev Limit can be changed


  • For Turbos only waste gates are allowed
  • Boost limit can be changed

Fuel System:

  • Carburetors and injection systems must not be changed in type, size and number
  • Manifold type may be changed, size slider limited to original
  • Fuel unleaded Ultimate 100 RON
  • Ignition timing free to change
  • Fuel Map free to change


  • Headers have to stay equal to production car
  • Exhaust size may be changed
  • No bypass valves
  • Catalytic converters and Mufflers can be removed, max. loudness 65

Body and fixtures:

  • Fog lights can be removed.
  •   Trims can be removed
  •   Lights can get a protective cover
  •   Putting Liveries is allowed.
  •   Interior can be changed. (Building an interior is not mandatory, thats just for the crowed thatt enjoys designing)
  •   Wipers can be removed and changed in position. At least one Wiper must remain for the windscreen.
  •   Number plates must be removed.
  •   No changes to the shape of the car!


  • Gearbox can be changed from the production car in type and gearing, no Continuous
  • Differential as on production car, Clutched LSD may be changed to Clutched Race LSD


  • Medium Race Tyres. No Magnesium rims.
  • Maximum tyre width:
    Up to 1150ccm 180mm
    Up to 1600ccm 205mm
    Up to 3000ccm 230mm
    Up to 4000ccm 255mm
    Up to 5000ccm 280mm
    Any higher 305mm
    Tyres are not allowed to stick out over the edges of the body.


  • Front and rear brakes must stay equal to production car. Size, force and Pad Type can be changed.


  • Undertray: None, Semi Clad, Fully Clad
  • No active aero
  • Setting of Front and Rear wings may be changed


  • Seats can be reduced to 1
  • Free Interior Choice to give possibility to add weight.
  • Standard, Premium or Luxury AM Radio

Driver Aids and Safety:

  • Steering: Generally must be the same as on production car, but electric and variable change to manual r&p, hydraulic systems can be changed to their manual counterpart
  • Safety: advanced 80s or 90s
  • Weight sliders are allowed to be moved freely
  • All traction aids must be deactivated


  • Springs may be changed, allowed types are: Standard, Progressive, Hydropneumatic
  • Dampers can be changed, allowed: Twin-Tube, Gas Mono-Tube
  • Sway Bars can be changed, only passive and offroad
  • Suspension Tuning is free. Camber is limited to max. -3.0. Toe settings max. +/- 0.40

Tank Sizes
up to 1000ccm 70l
1000-1400ccm 80l
1401-1600ccm 90l
1601-2000ccm 100l
2001-2500ccm 110l
Over 2500ccm 120l

Race mechanics

Races will be held at: Yanagrad Road Course (6 hrs), Al Rima Beach (6 hrs), Narnilla (8 hrs), Teberbergring (12 hrs), Ellisbury Road Course (8 hrs) from the Track Pack of Der_Bayer. (Automation World Track Pack)
Results will be determined in the style of la Marche using a revised and modified Spreadsheet, thanks to the permission of DerBayer. (!AnFEJXzJTPbPkjaD9r4jGAQDo2JP?e=CvF6Kx) Design beauty has no influence on lap times. Drivability and Reliability influence lap times. The higher the values, the less the influence.

Points system:
1 - 20 Pts
2 - 18 Pts
3 - 16 Pts
4 - 14 Pts
5 - 13 Pts
decreasing further with one point per position until 0

Submission phase for the race car open 'til 21st of April, 21:59 Zulu Time


Does this mean 4 full seats, or is a 2+2 layout ok?

2+2 should be fine.

1 Like

Few questions.
First, what do you mean by advertisement? Do you mean it should have it’s own forum page promoting the car, or just a poster or something in this page’s reply section? Secondly, how will races be run? Will they be done in BeamNG, or in automation itself? Also, another quick thing, will this be a rally or circuit racing?

An ad just means you present your car here in a reply to this post with a poster or pictures, sometimes people write pages of lore about their car.

The Races are basically an excel-calculation. The car will be run inside automation on the tracks named in the challenge to get a laptime. Furthermore the car will receive a little time penalty per lap based on drivability and reliability stat. Fuel consumption will be calculated, so that will lead to time in the pits for refueling. In “race mechanics” is a link to the excel file. You can build a car and enter your stats to see were you end up.

This rules out any and every body set (or more specifically, variants thereof) that lack provision for a second row of seats.

We’re assuming the splitter is a lip fixture, which should be front-mounted; the wing, on the other hand, should be rear-mounted.

No price limits for the production car?

Why limit us to just a clutched LSD when a helical or viscous unit can be fitted by 1985? Is this for cost reasons?

The seat rule is to get more or less body shapes fitting to the cars that started in german Gr. A races at the time.

Yes one front lip/splitter and max one rear wing plus a small spoiler. Thats to prevent having a lot of small aero fixtures all over the car.

I want to use Advanced 90s safety

The racecar budget depends on Desirability x Affordability of the car. That should naturally limit car prices. Anyways the max prices range for the racecar are alread given, so you probably want to stay below that.

Should there be a minimum desirability? Just to stop people from cheesing it somehow with a 0% desirability car that wouldn’t sell? But there are definientely some companies who can meet the 2,000 homologated road cars limit without selling any

To avoid total cheesing, I would suggest that everything with a normalized desireablity below 25 (according to my calculation) gets binned for being too commercially unsuccessful for financing the racing programm.

Makes perfect sense to me - anything that’s a slow seller as a road car wouldn’t lend itself to the “win on Sunday, sell on Monday” ethos, would it?

1 Like

I will change that. Its just important that its not an electrical system. According to the rule set the differentials have to work mechanically.

The requirement for advanced 80s safety and at least a standard AM radio on the race car is to simulate the fitment of not only FIA-mandated safety equipment, but also a two-way communications system between the driver and the pit crew.

Also, both the header type and size must remain unchanged between the road car and the race car if I’m not mistaken.

And are we allowed to adjust valve spring/lifter stiffness in addition to cam profiles?

Yes header has to stay unchanged, only the exhaust can be tuned.

Cam profile and spring stiffness can both be changed only vvt and vvl have to be present or absent like on the road car, but the vvl values can be changed if it is present in the road car.

Ergo, the race car’s fuel system configuration must be identical to that of the road car (in terms of type, size and number as well as manifold size), although you can change the intake manifold type.

Also, will we be limited to standard geometry turbos (with either journal or ball bearings)?

Turbos are just limited in the sense that you have to use a waste gate and only the boostlimit can be changed later on. (Aside from quality that can be changed always aside from locked areas)

Thanks. Also, if we can only used a clutched LSD of some sort on the road car, is the use of a clutched race LSD permitted on the race car?

And I suspect the minimum service cost limits may actually be too high - should they be removed or reduced?