The exposed carbon tub ties in with more visible carbon on the bucket seats, sills, centre console and a bulkhead that features stowage space for a race helmet. (evo.co.uk)
Luckily, after the F1 showed the world what it was made of, McLaren decided to continue the theme on its road cars, designing every model around carbon tubs ever since. (roadandtrack.com)
There are many reasons why Ferrari are not using carbon tubs yet which I think you should go and educate yourself on. (evo.co.uk)