Q: My 2017 Cadillac has an inside rearview mirror that is actually a video screen. While the image it shows of what is behind the car is bright and clear, I find it hard to focus on the image while driving. I see double at first before my eyes adjust. The dealer says there is nothing wrong with the mirror.

A: GM calls this a rear-camera mirror. As you note, it is a video screen that functions and looks like a standard rearview mirror. Nevertheless, it has several advantages that justify its added cost. Since it uses a camera located at the rear of the car, loading three large passengers into the backseat will not block your view of what is behind the car.

The image also appears to be wider than what you are likely to see when using a standard inside mirror, which may reduce blind spots and, therefore, make lane changes safer. Still, an over-the-shoulder glance and a check of the blind-spot warning system before merging or changing lanes is a must.

GM also claims that this mirror reduces glare and displays a crisper image in low-light situations. Unfortunately, drivers may find it’s difficult to focus on the image quickly.

Wearers of glasses with progressive lenses often find fault with this mirror, and even those who don’t wear glasses report experiencing a problem focusing quickly on the image after looking down the road far ahead. With a standard rearview mirror, the eye’s focus does not have to change since you focus on the image far to the rear of the car, not on the mirror’s surface. But when the mirror’s surface is a video display, you must focus on something that is just inches from your eyes. After you look far ahead, this adjustment can take a little time.

For individuals who find readjusting their focus bothersome, the video screen function can be turned off, which transforms the rear-camera mirror into a standard self-dimming mirror. By doing this, you should solve the focus problem.

WHISTLING IN THE WIND

Q: Ever since I had a replacement windshield installed, I occasionally get a wind whistle from the base of the windshield when encountering wind gusts. This problem never happens when the car is in for service, of course.

A: A wind whistle is a warning that the replacement windshield was not installed correctly. Where there is a wind whistle, there can also be a water leak that promotes rust, mold, and depending on the location, electrical problems. So, you should get this issue fixed right away.

There is also a matter of safety. Modern cars have windshields that are glued in place. Once the adhesive that is used forms a proper bond, the windshield actually becomes a structural part of the car, helping to support the roof in a rollover accident. If the adhesive application was improperly done, or if the car was used too soon after the windshield was installed (which can weaken the bond between the glass and the car’s body), air and water leakage can follow and, as a result, compromise the full strength of the glass in a crash.

Further complicating this situation, in cars that deploy the passenger-side airbag from the top of the instrument panel, an improperly bonded windshield poses a risk to the passenger since this airbag may not deploy correctly to protect the passenger in the event of an accident.