Mazda, BMW, Tesla, and a half-dozen or so other automakers have decided to eliminate AM radios from their new electric cars, largely because the electronics in the cars’ motors interfere with AM reception, which causes the radio signal to fade or break up.

Meanwhile, Hyundai, Kia, Subaru, and a separate cast of car manufacturers have chosen not to drop AM radio, having concluded that the static problem can be minimized through preventive design and technical fixes.

On the subject of dashboard AM radio reception, the automotive industry is plainly divided. In one camp are those who think that AM has so far outgrown its appeal to car buyers that it no longer justifies the design hassles required to make it available, especially in electric vehicles. In the other camp are those convinced that AM radio is a feature that drivers continue to value highly enough that overcoming the signal interference is worth the added aggravation and manufacturing costs. Both positions seem plausible.

Which is better? That’s a perfect question to submit to the wisdom of the competitive marketplace. After all, there are dozens of companies making new cars, almost 18,000 US dealerships selling them, and millions of customers annually buying them. Their collective wisdom will make it clear whether it makes more sense to keep or lose AM radio in new cars.

Unless politicians get in the way.

Senators Ed Markey of Massachusetts and Ted Cruz of Texas have introduced legislation that would deprive automakers of the right they have always had to decide for themselves whether to include AM radio in the cars they make. Under the proposed “AM Radio for Every Vehicle Act,” AM radio would be mandatory in all cars sold in the United States and would have to be provided as a standard feature at no extra charge.

Why should this be any of Congress’s business? The pretext for Markey, Cruz, and their cosponsors is that AM radio stations are used to broadcast emergency information during natural disasters or other critical events. Since AM radio has a wider broadcast range than FM and can be heard by a larger audience, especially at night, it has long been a part of the National Public Warning System. “Broadcast AM radio is an essential part of our emergency alert infrastructure,” Markey insists. “The truth is that broadcast AM radio is irreplaceable.”

No, the truth is that, for many people, broadcast AM radio was replaced long ago — including for emergency messaging.

Today those messages are apt to come through the cellphones that are owned by 97 percent of American adults. Virtually all cell phones are set up to receive Wireless Emergency Alerts, which the Federal Communications Commission describes as “an essential part of America’s emergency preparedness.” Since 2012, according to the FEC, such alerts have been sent to cellphones and other mobile devices “more than 78,000 times to warn the public about dangerous weather, missing children, and other critical situations.” Moreover, wireless alerts are free, all major providers transmit them, and they are unaffected by network congestion. Unlike with radio, cellphone users don’t have to be actively listening or tuned to a specific frequency; they need only have their cellphone handy and turned on.

Cellphones aside, there are numerous channels besides AM radio for emergency information. Warnings reach the public through cable and broadcast TV, through the Internet, and through FM and satellite radio. Even in vehicles that don’t include AM radio as a dashboard feature, motorists can readily tune in to AM stations through streaming radio apps like iHeartRadio and TuneIn. For that matter, a Tesla or Mazda buyer who wants to be sure of having AM radio access can buy a cheap AM/FM transistor radio and keep it in the glove compartment.

None of this is to deny that AM radio still draws plenty of listeners, including tens of millions of talk-radio and sports fans. It is to deny the preposterous claim by Markey, Cruz, and other politicians that car manufacturers should be forced to include an AM radio button in their new electric vehicles as a matter of national security. When automakers decided 90 years ago to begin including AM radio as a standard feature, it wasn’t because of a decree issued by Washington. It was because they perceived a market demand for the feature and adapted to meet customers’ needs.

No congressional diktat is required now either. Automakers are far better attuned to the wishes of car buyers than Congress will ever be and can figure out for themselves whether or not AM radio should be discontinued. As different companies pursue different strategies, the marketplace will clarify which is best. Grandstanding legislators have nothing useful to contribute to the process. The best thing they can do is back off.