Shell Eco-Marathon Vehicle Modelling

The aim of the Shell Eco-Marathon competition is to build a car to be as efficient as possible. Our 2024 year's team of 12 inherited the 2023 team's competition vehicle, with the primary aim of ensuring it is rule compliant and is able to run on the track, and a secondary goal of ensuring it is competitive. I ensured compliance throughout the building process using a spreadsheet, in collaboration with another member of my team. The vehicle ultimately passed tech inspection successfully, so our efforts were sufficient.

From the beginning, I recognized that building a vehicle model would be essential so we could most effectively allocate our limited time, money, and attention to create a competitive car. I built a point mass vehicle model with rolling resistance, drivetrain efficiency, and drag along with support for the motor's characteristic curve to estimate efficiency. This allowed me to conduct sensitivity studies to determine how changing major vehicle design parameters affect our ultimate energy usage, which allowed us to set quantitative design targets. 

I discussed my sensitivity results with the team to set  reasonable design goals. We aimed for ~30% reductions in drag and mass which we achieved. I considered rolling resistance, but we did not plan on manufacturing our own tires and we generally had little data on that so it was not considered as something we could change freely.

I also conducted driving strategy studies which found 'hypermiling' was most efficient, where we maintain an average speed by running the motor at its torque for optimal efficiency. I also ran some simple simulations to determine the course completion time using this type of driving strategy. From this, I also found that allowing the vehicle to coast down at the very end to near 0 mph uses more electricity due to the higher average speed that needs to be maintained before this.