DEAR CAR TALK: I recently purchased a 2017 Hyundai Elantra, which I love.

Heading eastbound (downwind), I have been known to get 50 mpg on the highway. But there’s one thing about it I don’t understand.

While sitting in the driveway listening to the last 10 minutes of your radio show, Car Talk, I get a “low battery” warning, and I am directed to restart the engine.

Thirty years ago we could sit through a double feature at the drive-in, listening on the radio with the ignition switch on “accessory,” and still start the car later. What’s changed? – David

RAY: What’s changed is that you now have a computer in your car that can remind you when you’re running down your battery. And the computer can take preventive action and shut down your car if you don’t respond to its warning.

Next time you see this warning, try ignoring it. What you’ll probably find is that after a few more minutes, the car will shut itself off. It’ll probably give you another warning first, and say something like, “Shutting down soon, David. I mean it.”

As a side benefit, when it does shut down, our show will be cut off and you won’t have to listen to rest of it.

Why would the car’s computer be programmed to do that? Well, here’s one scenario:

Your car has keyless ignition. Let’s say you park the car but you accidentally hit the “start-stop” button twice when getting out. So instead of shutting off the car, you’ve left it in accessory mode.

So the car sits there for 10 or 15 minutes, and then says, “Hey, David, you still here?” If you’re there and just listening to the radio waiting for your wife to clean out the shoe rack at Target, you can restart the car for 30 seconds and keep listening.

But if you’re not there … if you’re already inside watching Geraldo while nursing a growler of Shark Spit Lager, your lack of response will cause the car to shut itself off to save the battery.

And while listening to the radio for 10 or 15 minutes would never run down your battery, it’s possible that if you left the car in accessory mode from 7 p.m. to 7 a.m., you might.

So it’s the car looking out for its own best interests, David. It’s the Hyundai Elantra Selfish Edition.

Got a question about cars? Email Car Talk’s Ray Magliozzi by visiting the Car Talk website, www.cartalk.com.