New Scientist Publish My Letter

Just a quick bit of boasting: New Scientist has published (an edited version) of a letter I sent in regarding claims made for a three-wheeled electric car, the Aptera (left), “Its radical design minimises air resistance, right down to little touches such as tucking the windscreen wipers below the airflow. As a result, the entire vehicle has a drag coefficient of just 0.15 – making its drag roughly the same as that caused by a single large wing mirror.” (emphasis mine) 

Sanity checking a striking claim

Interpreting technical data can be a tricky business, as demonstrated by an interesting article in last week’s New Scientist magazine.  In a fascinating review of the recent progress made by manufacturers of electric cars the journalist tripped up in his discussion of the aerodynamic drag figures claimed for the Aptera, a two-seat electric car (the word refers to wingless insects – appropriate enough as the car does look like someone has pulled its wings off!).

“…the entire vehicle has a drag coefficient of just 0.15 – making its drag roughly the same as that caused by a single large wing mirror.”

This is a very striking claim, however, we shall see that some simple maths and a few estimates are all that is needed to show that the journalist has made a mistake here.