Cruze Eco aero wheel inserts
After many many test prints in PLA to find the right geometry and fit I've come up with an insert that fits into the larger spoke openings in the 17" wheels found on a first generation Chevy Cruze Eco. These snap into place with no fasteners and have been tested up to speeds that I will not disclose publicly as well as about 1500 miles of driving so far.
Testing at 80 mph (my daily commute speed) has shown a roughly 3.5% improvement in fuel economy (bumped from 28.83 mpg to 29.80 mpg on E85). Nothing ground breaking by any means, but at least a measurable improvement. Since my commute is across flat terrain and predominately interstate I'm not concerned about brake cooling; even so, the inserts can be easily popped out by hand in-situ should I ever decide to go someplace with more terrain variation like Colorado.
Printed in ASA with 4 walls, 5 top layers, 6 bottom layers, and 30% infill. Each insert weighs about 34 grams and have caused no perceivable change in tire balance.