Can the old-school Cadillac CT5-V Blackwing stand up against the modern Audi RS7 Performance and the plug-in hybrid BMW M5?

I bought this Audi RS5 crash damaged from auction for my girlfriend to use as her daily car. Now i have repaired it i need to get it back on the road and sort the exhaust noise. The Audi RS5 has a 4.2 ...