In 2018 i was lucky enough to work with one of the uber talented demo teams at Unity technologies. The project revolved around showing off new tech for the Unity 3D engine - and i was approached to help flesh out some of the many car designs needed for the tech demo.
The dev. time was fairly short, but it was super fun to come up with designs for the different vehicles almost on the fly - most designs were achieved within a days or two's work (depending on detail and iterations), so turn-around was super fast on these.