TLDR: I love my Garmin RTL 510
1. It alerts me of up to 3 cars behind as far as 140 meters - 82 bike length behind. You’ve read that right. I confirmed it on the road.
2. It has really bright LED even in daylight. Garmin claims it is visible up to a mile away in daylight. I think it is close to that.
3. It lasts between 6-15 hours depending on the mode. When connected to Garmin computer it alerts me if the battery is low.
4. It is plug-n-play setup if you already own a Garmin computer and it is fully integrated at the software level. When active, the radar is visible on all screens (even in settings) and hides away when there are no cars around.
5. It beeps, flashes and shows me dots for each car. How fast those cars are coming and how far they are behind.
If you have this radar system, I’d love to hear from you with your experience. If I missed anything and you have more questions, please ask them here.
Ride on and be safe out there.