In the U.S., individual wireless carriers routinely claim to offer superior service often in the form of “coverage” in their advertising. For example, Verizon claims to offer the most robust 4G/LTE service coverage in the U.S. (RootMetrics). T-Mobile claims to have the “fastest and most reliable” 5G coverage (umlaut).

These claims took on legal dimensions a few years ago when the Federal Communications Commission (FCC) was preparing to divvy up billions of dollars in subsidies for rural broadband. Suddenly, the regulator was requesting coverage maps from carriers under pain of perjury.

The wireless carriers submitted their coverage maps to the FCC reflecting their ability to deliver wireless to particular geographic areas. Individual U.S. states and the FCC conducted their own tests attempting to confirm the accuracy of the maps provided by the carriers.

Testing included everything from driving around in vehicles with multiple smartphones from representative carriers to off-road hikes to measure the availability and quality of connections. The verdict was bleak.

States and the FCC discovered what consumers intuitively already knew, that the carrier-provided coverage maps were seriously flawed. The FCC delayed its funding plan and does not expect to resolve the coverage mapping and related funding issues until 2023.

The kerfuffle highlights what some might consider an open secret – that wireless geographic coverage is unreliable and definitely not ubiquitous. For users of smartphones this reality is vexing, but generally not fatal. It is accepted, known, a given.

Most mobile phone users quickly become familiar with their carrier’s “white zones” and simply try to avoid them.  For drivers of connected cars, though, the proposition has different dimensions that can impact the functioning of on-board safety systems or navigation.

In fact, everything about coverage and measuring it is fraught. To properly measure coverage requires thousands of dollars in carefully calibrated equipment and the only practical method for implementing a scalable solution is to use a vehicle-mounted arrangement and drive the roads in the relevant area.

But carrying the measuring equipment inside a vehicle poses its own reception compromises and fails to deliver a reception experience equivalent to the performance of a smartphone in the hands of a consumer. So the finest measurements of coverage are ultimately unrealistic.

Worse than that, carefully calibrated measurements of coverage are merely an expensive snapshot. “Coverage” or, really, reception can vary by time of day, weather conditions, volume of traffic, and interference. This is to say nothing of coverage/signal strength measured away from roadways – such as in homes.

So, while the FCC continues to wrestle – along with the industry – over the question of proper coverage measurement metrics, consumers continue to see advertised claims of superior “coverage” or “service” from wireless carriers based on no real agreed standard of measurement. The entire proposition is a farce.

But, again, the issue takes on a greater degree of seriousness for connected cars. Regulators are increasingly requiring autonomous cars to support remote control or teleoperation. This would suggest a need-to-know familiarity with cellular coverage to ensure an available connection.

Coverage is also essential to delivering cellular-based automatic crash notifications (eCall in Europe). Automatic crash notification systems, such as General Motors' OnStar, are not equipped with analytic tools to determine when and whether a cellular connection is available.

And, finally, safety systems such as the soon-to-be-mandated Intelligent Speed Assistant (a Euro-NCAP requirement for all cars from 2024) will need predictable cellular connections to render the relevant local speed limit in instrument clusters. Of course, measuring coverage/service availability for an embedded cellular device is an entirely different proposition from measuring coverage for a handset.

So, regard those coverage/service claims from your carrier with a grain of salt.  Wireless carriers will never ever, not ever, be able to offer ubiquitous connectivity.  And we may never know precisely the availability of connectivity on the road ahead but - as two industries, wireless and automotive – we have an obligation to try to figure this out.  And try we will.