Do aero wheel covers actually improve MPG?

Short answer: yes, measurably, and less than you are hoping.We sell these, and we would still rather you buy them for how they look than be disappointed by a fuel bill that barely moves.

Why wheels matter aerodynamically at all

A wheel is a bad aerodynamic shape doing a difficult job. It is a rotating object sitting in a cavity, partly exposed to oncoming air, with spokes that pump air sideways as they turn. Wheels and wheel wells account for a meaningful share of a car's total aerodynamic drag, which is why they get so much attention from manufacturers chasing efficiency numbers.

Closing the face of the wheel reduces the turbulence the spokes create and smooths airflow down the side of the car. That is the whole mechanism. It is simple, it is real, and it is not dramatic.

The evidence that it works

• Manufacturers do it on purpose. Aero covers ship on efficiency-focused models, including EVs, specifically to improve range. Nobody adds tooling and cost to a production car for nothing.
• Land speed racers did it first. The 1950s moon discs were credited with roughly five horsepower for the outer disc and about five more for the inner one. See the history of moon discs.
• Trucks run them for economy. Wheel discs on modern trucks exist for fuel savings, not styling.

The honest limits

There is good evidence aero wheels improve efficiency and range, but the difference is not dramatic, and how much you get depends heavily on the rest of the car. A vehicle that already manages airflow well around its wheels has less left to gain. A car with wide wheels sticking out past the bodywork has more.

Three things make published numbers hard to trust:

1. The gain is small enough to be swamped. Tyre pressure, ambient temperature, headwind and how you drive will each move your economy more than a wheel cover will.
2. Manufacturer figures come from full-car development. A factory aero wheel is designed alongside the underbody and the wheel arch liners. A cover added later works alone.
3. Nobody publishes a controlled test of aftermarket discs.Any specific percentage you see quoted for a bolt-on cover is almost certainly borrowed from somewhere else.

So we do not put a number on it, and we would be suspicious of anyone who does.

What about brake cooling?

This is the fair objection, and it is the reason our designs are not all closed. Covering a wheel face reduces airflow to the brakes. For normal road driving that is a non-issue, and our closed design carries cooling ports for exactly this reason. If you drive hard enough to care, the open lattice design moves considerably more air. If you actually track the car, do not fit wheel covers of any kind, ours included. That is covered inare aero wheel covers safe.

So why buy them?

Because of what they do to a car. That is the honest reason almost everyone fits them, it is a perfectly good reason, and pretending otherwise would just set you up to feel cheated. The aerodynamics are real and they are a bonus.

If you want the version that moves the most air, look at the open lattice design on the three designs.