Reflections on side mirrors: testing drag vs. MPG

metrompg.com series | Highlighted on Fuelcons

This experiment, which was published on metrompg.com, aimed to explore the influence of side mirrors on a vehicle’s drag and fuel efficiency. The motivation behind this study stemmed from the adoption of video cameras instead of conventional side mirrors in high-efficiency concept cars, leading to a desire to ascertain whether such alterations yielded tangible advantages. The investigation was carried out using a “Blackfly,” essentially a black Pontiac Firefly, wherein the stock non-folding driver’s side mirror was replaced with a folding mirror from a 1993 Suzuki Swift 3-door, featuring an aerodynamically optimized hinge.

The experimental procedure involved comparing fuel efficiency under two conditions: (A) with both mirrors in place, and (B) with the passenger mirror removed and the driver’s mirror folded. The testing was conducted at a speed of 54.7 mph (88 km/h), with cruise control engaged prior to entering the test section. To eliminate any effects of wind or grade, the results from runs (A, A, B, B, A) were averaged in both directions. The average MPG (US) for the A runs was 55.24 (4.26 L/100 km), whereas for the B runs, it was 56.51 (4.16 L/100 km). This represents a 2.3% increase in fuel economy in terms of MPG (as well as a 2.3% reduction in fuel consumption measured in L/100 km).

In conclusion, the experiment demonstrated a noticeable enhancement in fuel efficiency through the modification of side mirrors, corroborating the initial hypothesis that side mirrors could indeed exert a significant influence on a vehicle’s aerodynamics and MPG.

Source: metrompg.com