"arbitrary" means the poster doesn't know what there is actually, but wants to blame EU anyway

Any rule that allows G600s and disallows Jimnys is arbitrary. The G600 doesn't become any more eco-friendly if you also sell an electric car.

It's a regulation which is, let's say, "mindful of social hierarchy".

It's not arbitrary and it's not just CO2. The Euro 6 and upcoming 7 standards also test for carbon monoxide, unburnt hydrocarbons, nitrogen oxide, and particulates from the tailpipe, brakes, and tires. The Jimny couldn't pass on those and Suzuki decided it wasn't worth the price of compliance to add things like gas particulate filters and change the brake pad material.

Mercedes does not make a G600. If you're not talking about Mercedes then you should specify a manufacturer because I can't figure out what car you mean.

Nice nitpick. For you effort you get to choose between GLS600 (13.7l/100km) and AMG G63 (14.7l/100km).