The CLA45 AMG does have a torque advantage with 332 lb-ft of torque to the 316 lb-ft of torque in the R8. Both have all wheel drive but the CLA45 AMG has a dual clutch transmission while the R8 has a 6-speed manual. So how does an entry level AMG sedan do against a $100k+ V8 Audi sports car (in the rain) ?
Incredibly well. The cars are surprisingly close until the top end of the 8000+ rpm Audi V8 allows it to open a slight gap. This race is much closer than the R8 owner likely expected. The less powerful entry level four cylinder Mercedes sedan sticks with the R8. All while having half the cylinder count, half the displacement, and half the price.
How can one not be impressed with what AMG has done with the 45 models?