Take a 1,200-hp, twin-turbo Cadillac CTS-V coupe. Put it on that chunk of highway down in Texas where the speed limit is 85 MPH. How fast will it go?  220.3 MPH. The Texas Highway Patrol approved the run…they wanted to test speed cameras they have installed on the road. The guy who built the car, John Hennessey says it might have gone to 230 in another mile.