Low drag mirrors

[cfeng]

i use a water tunnel in my lab. i've been thinking about this. with a properly designed rear wing on the hatchback, it may be possible to increase fuel economy.



the top picture is similar to a stock yaris, air swirls in vortex patterns, which means that not only does the yaris need to propel itself forward, but spend considerable energy into moving air. with the correct rear wing, there could be less separation in flow at end and less movement in the air, similar to the bottom picture. i found this picture online, the second picture is misleading because it represents an ideal case with virtually no separation in flow.

the antennae will disturb how the eddies are shed, reducing wasteful swirling of air (reduce a little). similarly, if a wing is designed to reduce the size and number of eddies from forming by increasing turbulence at the rear of the car, the car will have less drag and overall better efficiency.