For the highest revving street-legal 6-cylinder engine currently for sale, head over to Porsche to sample its screaming 4.0L flat-6.

Confidently sticking to its guns, Porsche went its own way to create one of the best cars on sale.

Rezvani's carbon-fiber rebody of the 992-generation Porsche 911 added the giant tail and widebody rear of the legendary ...