I was riding alongside one of those cars one day and the driver kept getting on the gas and immediately backing all the way off. Its was making a ton of snap crackling pop noises on decel.
Nice looking car though.
He turned on the Dynamic Exhaust. Those zany Jaguar engineers set up Dynamic exhaust so that it opens the butterfly valves in the exhaust to make more noise and adds a little gas and changes some of the engine settings when you let off the gas to get that crackling pop. It's addictive.
You can drive around in quiet mode.