I will pass over the fake lens specifications like 177 degrees (maybe real 90 degrees?) found on many cheap and poor cameras.
Many people are thinking that if they will buy a camera with a larger wide angle they will record more image. This is right, if the wide angle is real, but you must not forget that using this type of lens all objects in front of the camera are zoomed out, are far away than the real situation.
The big drawback about having objects far away is for example when you want to read car license plates. The closer they are, the better is the reading of them. More than that, if the interesting area for you is on the sides, is OK to have a wide lens because you will have more chances the object to be recorded , but because on the lens sides the image is distorted your chances are even smaller to read the characters from the plate.
But why is important to have a clear image regarding car plates? Most of you know if you are going to court and want to have some evidence which will be approved by the judge, you must have the number of the car. If you are going with a nice wide picture of a common white Prius on court without showing the registration number you have big chances to have nothing against the Prius and his driver.
We are not buying dashcams to make some movies or entertainment, or to feel like a cop, we want them to protect us if some event will happen. And always the details are important.
I consider 120 degrees is enough for a dashcam. Of course angle is not everything we must not forget the quality of the lens, less distortion, CMOS size, quality of the recording, but we already know what we want regarding these features because we can watch samples.
enjoy,
Mtz