In the end I'm gonna use the standard motion detection because I want to capture people too. There are videos of people keying cars and the motion detection parking mode caught their face and led to finding the person.
I can see it being useful if you're not worried about getting keyed, but live in a high traffic area and don't want the motion detection constantly getting triggered which will fill up your memory card much quicker. But then you gotta back into parking spots always and make sure the radar is facing out.
Although we’re off topic for the comparison of two cameras, I’ll comment here on the subject of radar.
It seems to me that the radar really benefits a niche use case, that is people who leave their cars for extended periods of time and want ultra energy saving mode. Whether you’re running off an additional battery or not, using the radar means the camera only wakes up when car movement is nearby, and it only records to the card if the accelerometer is triggered. There is a similar recording mode without the radar module that just uses the camera to detect movement and record to the card IF the accelerometer is triggered. There are also other parking modes, but I’m comparing as closely apples to apples. Therefore, the radar module isn’t so much about preventing a memory card from filling up, as it is about power reduction.
Now if you use your car regularly, such as most people, I can’t see how radar benefits you. On the other hand, if you live in a major city, and take public transport during the week and only use your car on a weekend, I could see how you might be interested in the radar module. While it won’t necessarily be for everyone, such as those who park in the street and worry about side-swipes or bumps from the rear, it could be useful for those people who park in a parking garage.
The other use case where I could see it being of value is if you leave your car in airport parking for a trip, and anticipate being away 3-10 days. With a battery for your camera and the radar module, you could maintain a safety recording/monitoring of your car while you’re away on holiday. Of course, if you take a taxi/limo/Uber to the airport, or get a friend to drop you when you take your holidays the radar module isn’t that useful.
So there is, as I see it, are the two best use cases for the radar module: people who live in a city, who only use their cars infrequently, and park in a parking garage, and people who take their car to the airport and leave it in long term parking while they’re away on long trips.
99% of everyone else who use their cars regularly can probably be better served without the radar module and adjusting their parking mode, and/or buying an additional battery.