Europe taxes cars based on the size of the motor, so the larger the displacement, the more tax you pay. That's on top of the premium for specific models, especially cars like the Camaro. That is why an SS Camaro will run you almost 80-90k in the UK but 30-40k here....
Additionally, this is why GM brought back the 2.0L turbo so that they could start making real headway into EU with sales.