Cadillac reckons its CTS-V is the fastest production V8 saloon in the world, but extreme car fettler Hennessey Performance clearly doesn't think this is enough.
So, instead of making do with 556bhp, you can now have it turned up to 707, which means 0-60mph in 3.3 seconds and a top speed of 211mph. In what is, aerodynamically at least, a box on wheels.
The extra power is achieved by tinkering with the usual tuning suspects (engine management system, cam, induction, exhaust etc) and, we hope, the brakes.
See it in action during quarter-mile testing, complete with inappropriate emotive piano soundtrack: