It's been quite a while since the rules were changed back in 1997. They now say that World Rally Cars must be built upon a production car with a minimum production run of 2500 units. A number of modifications may be made to the car, including but not limited to:
* Engine with displacement of no more than 2.0 litres
* Turbocharger with Anti-Lag System
* Four wheel drive
* Sequential gearbox
* Aerodynamic parts
* Weight reduction to a minimum weight of 1230 kg
* Chassis strengthening for greater rigidity and safety enhancement (rollcage)
In other words, the closest we get to homologation nowadays is that they have to make 2500 cars with the same basic shell, and after that they can pretty much modify what's inside however much they like without having to produce a road-going version.
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