Tradecraft: The effects of an EMP on automobiles (Spoiler alert: the movies are wrong)

(TFC) – The threat of an Electromagnetic Pulse (EMP) knocking out all of the vehicles in the country is popularized by just about every sci-fi post-nuclear war movie in history. A twist is that it will only effect those vehicles with lots of electronics. These scenes are based on a public belief in what really amounts to a nuclear myth.

The United States has an EMP Commission. It has extensively studied the impacts of EMP. If your car isn’t running, it will most likely be fine. Out of 37 vehicles with electronics tested, not a single one malfunctioned. If it’s running, there will probably be some effects, but not catastrophic failures. At average EMP levels, only 3 cars stopped running. All three restarted. Other than that, it was blinking lights and minor nuisance issues. One car needed some repairs to the instrumentation in the dashboard. At higher EMP levels, it could be expected that 2 out of 3 cars would suffer some nuisance. Out of those that suffer effects, only a small fraction are expected to experience major issues like stalling.

The myth persists because of the addition of more and more electronics to automobiles as time marches on. At the same time, microprocessors have become more protected against EMPs, so the expected vulnerabilities aren’t surfacing.

The EMP commission had this to say in its 2008 report:

The potential EMP vulnerability of automobiles derives from the use of built-in electronics that support multiple automotive functions. Electronic components were first introduced into automobiles in the late 1960s. As time passed and electronics technologies evolved, electronic applications in automobiles proliferated. Modern automobiles have as many as 100 microprocessors that control virtually all functions. While electronic applications have proliferated within automobiles, so too have application standards and electromagnetic interference and electromagnetic compatibility (EMI/EMC) practices.

Thus, while it might be expected that increased EMP vulnerability would accompany the proliferated electronics applications, this trend, at least in part, is mitigated by the increased application of EMI/EMC practices. We tested a sample of 37 cars in an EMP simulation laboratory, with automobile vintages ranging from 1986 through 2002. Automobiles of these vintages include extensive electronics and represent a significant fraction of automobiles on the road today. The testing was conducted by exposing running and nonrunning automobiles to sequentially increasing EMP field intensities. If anomalous response (either temporary or permanent) was observed, the testing of that particular automobile was stopped. If no anomalous response was observed, the testing was continued up to the field intensity limits of the simulation capability (approximately 50 kV/m).



In short, it’s unlikely you need to build a faraday cage in your garage to protect your vehicle.