When you can’t rely on people to tell what happened after a crash, a dash cam may be your only good backup. “My client says he had a green light while driving through an intersection,” said Ben Schwartz, a personal injury attorney. “But another driver, who came through the same intersection and struck him, claims he had the green light.” Who’s right? It’s in those situations when a dash cam can be your most reliable — and, often, only — eyewitness.

I’ve been writing about cars and car electronics for more than 25 years, and I’ve used more than 40 dash cams in my car while reviewing them for Wirecutter. I’ve found that I get asked for advice about dash cams right after someone has been in an accident or experienced a too-close-for-comfort miss. They want to be ready ”next time.” Here’s what people ask me about most often.

What to look for

While you’re driving, a dash cam records everything that’s in front of your car, from crazy drivers to stunning vistas to, yes, viral-ready mishaps. Normally, it records new video over the oldest footage on its memory card, but if it detects a crash, it automatically saves that section of video from being overwritten. That’s your insurance. (You can also manually save video.) But you can find huge differences between models, so here are the features I look for:

A sharp video image : Hands-down, this is the most important consideration for me. If you can’t see the fine details — including the license plates of surrounding cars — the dash cam could let you down when you need it most. The sharpest video I’ve seen has come from higher-resolution models that record in 1440p (a.k.a. Quad High Definition, or Q.H.D.) or 2160p (4K). I usually see a big drop-off in 1080p (Full HD) video, which is what most dash cams record. And I would never recommend that someone buy a 720p model.

Easy-to-use controls : Reviewing video and adjusting the camera’s settings can be either super easy or annoyingly difficult, depending on the dash cam’s design. Models with a touch-screen are the easiest to use. In contrast, many dash cams have small, hard-to-use buttons or place the buttons out of the driver’s sight, so you have to navigate them by feel. That’s a hassle.

A versatile windshield mount : If you’re worried about theft, you should choose a dash cam that’s easy to remove from its mount and to reinstall. The simplest models have powered magnetic mounts that let you pop the unit on and off without having to hassle with a cord. How the mount attaches to the windshield also makes a difference. Those that use an adhesive pad are secure but very difficult to reposition or move between vehicles. Suction-cup mounts are much easier to move but can take up more space on the glass. Fortunately, many models give you a choice.

Owner reviews and ratings: Although I always check a model’s owner reviews and ratings, they’re definitely not something to rely on. A lot of dash cams with high ratings on Amazon, for example, get low grades — such as a D or F — on Fakespot. Still, owner reviews are good for learning about common problems.

The best Wirecutter tested

I’ve had the best overall experiences with the Nextbase 522GW, Wirecutter’s pick for the best dash cam, and its smaller, less expensive sibling, the 422GW. Both record in 1440p, and they deliver some of the sharpest video I’ve seen at their price point.

In our tests, details in their footage were crisp, and I could easily read license plates that were fuzzier — or indecipherable — in footage from other dash cam models. Both of our favorite dash cams have bright, responsive touch-screens, as well as powered magnetic mounts that make them especially easy to remove or to reinstall on the windshield. The Nextbase smartphone app is also the best I’ve seen from a dash cam company.