External visual changes to the Elemental RP1 production car are subtle: the rear section is slightly lower to improve airflow and enhance rearward visibility, the aerodynamics have been tweaked, with larger side vents now incorporated into the bodywork behind the cabin to improve airflow to the engine, and further work has been done on the underfloor airflow.
“It’s been an exercise to improve the car, reduce the weight, increase the stiffness and the car’s adjustability,” said Hall. “We're very comfortable that the production car will be considerably more enjoyable to drive. The whole package is stiffer by about 30% - that’s the main area where I think people are going to notice the difference.”
Aerodynamics expert Fowler used computational fluid dynamics software to refine the body shell shapes and enhance the aerodynamic properties of the underfloor, including the front and rear diffusers and completely sealing off the car's underside to enhance airflow.
Fowler said: “We were very happy with what we had from the start, but there were one or two areas that didn’t really work, which were easily corrected. The whole underside of the car has been developed as a single entity effectively, rather than just put on a front splitter, rear wing and simple diffuser. We tried not to put a rear wing on this car - that would have been an easy win but also would have increased drag and we’re trying to keep that as low as possible.
“Using the underfloor to enhance the aerodynamics obviously reduces drag as well. Our front splitter is a fairly simple [marine plywood] plank but we’re getting a lot of downforce from it. So there is loads of scope to actually develop the front splitter and give it a special profile to produce serious downforce, which we can balance off at the rear.
“We spent as much time developing the diffuser as we did getting the shape of the bodywork. It’s made using a proper race car philosophy, of sealing off the bottom surface of the car. The floor acts as an aerodynamic device, but it also protects the carbonfibre tub as well.”
At the heart of the car is a 68kg carbonfibre tub, built to a higher standard than that of the prototype. For its composite work, Elemental has partnered with a Portuguese-based specialist called Optimal Structural Solutions. The sides of the tub have been made thinner to improve occupant space, with extra plies of carbonfibre added to the structure to retain the same stiffness as the thicker prototype passenger structure.
Read more about how the Elemental RP1 was born
“When we let potential customers sit in the car at Goodwood last year, some very tall people struggled for arm and shoulder room,” said Hall. “There is now considerably more room, and we’ve also dropped the floor and the seats to guarantee that someone 6ft 6in tall can fit.”