TF mini don't work

I have two TF-minis and one Sharp LIDAR. All three work VERY WELL inside the house at distances up to 3-4 meters, but outside in overcast sky (not sunny) they do not detect moving objects as I would like. I'm trying to count vehicles that go by on the highway at relatively low speed, max 60 kph, and the Lidars just don't do it.

There are some new Lidars at DFRobot, more expensive but show promise. I don't want to spend MORE money and be disappointed, so I'm wondering if anyone has experience with these? Right now I'm back to ultrasonic, which has it's own problems, but Lidar seems to be the tech I need.

Sure wish I could get a sample to try, for free.

I had an almost working Laser detection where I bounce laser off a mirror and back, but aligning the sensor with the returning laser light proved extremely difficult. I had it working in simulation (in my shop) such that it could discriminate between 5 vehicles by timing how long the beam was broken.