Yes, you can have a supercar with a V6.
There was an awful lot of debate about the Ford GT Concept's engine a few years ago at Detroit. A twin-turbo EcoBoost V6 in a supercar, and one, no less, that bears the name and represents the spiritual successor to perhaps the greatest car Ford ever built? Yes, Ford's choice to go with the twin-turbo V6 was controversial, but it's paying off big time. With 647 hp, this is definitely not your normal V6, but it does clearly prove that downsizing and adding turbos can work brilliantly.
Motor Trend's Angus MacKenzie was one of the lucky few non-buyers to drive the 2017 GT on both the road and track, and aside from a few very nitpicky criticisms, MacKenzie was nothing but impressed. Remember, MacKenzie has been in the business for a long time, beginning his career in his native Australia.
He knows cars better than most, so it's fair to say we trust his judgement here. Ford has no doubt created a supercar game changer, something that wasn't initially built as a road car with added race car components, but a racecar for the road (with Le Mans in mind, of course). If this is how modern supercars are powered in order to achieve the best numbers for both performance and fuel economy, then that's just fine with us.