That’s a snug fit!
The rear end of the car has also been slimmed, while sporting a squarer shape (see yellow arrows). One can also spot a new aerodynamic vane ((see blue arrows), which fits the lines of the enveloping engine cover. A similar device has already been seen on the all-conquering Mercedes.
The engine cover also wraps the transmission and exhaust more snugly, with the latter sitting at a lower level (compare white arrows).