Driving yesterday I saw a guy driving a Honda Del Sol with some type of transmitter boxes mounted on the trunk lid.
Any idea of what these are for?
No, and you should have blurred out the license plate; you’ve just invaded this person’s privacy and possibly endangered them.
How so? The license plate is publicly displayed on the streets every day.
Women wearing skirts are publicly displayed on the streets every day.
Just because hardly anyone takes up-skirt photos of them, it doesn’t mean it’s NOT an invasion of privacy if you did it without permission.
There’s no expectation of privacy if you display a license plate in public.
It’s possible he is working for SkyHook.
I saw several license plates on my way to work today.
Should I have my memory wiped?
And what does any of this have to do with the OP’s question? Five response and none dealing with the OP’s questions. If only this place had rules. 
It’s some sort of test equipment. Not sure where you are getting transmitter boxes from, as they look hard wired into the trunk. That’s about all that can be determined without actually stopping the guy and asking. Then you could also ask him if it’s OK to post a photo of his car and plates on the internet but it’s too late now. Perhaps since we know his license number we could track him down and ask.
Not a valid comparison. Taking ‘up skirt’ pictures requires an intent to invade privacy. This is just photographing a public street.
Post #5 offered an idea. But mostly we don’t know. Post #2, on the other hand, raised a question we do all have an opinion on.
Here’s a link to a page about automated license plate scanners. The photo shows the trunk of a police car, with two boxes on the left and right sides. They look similar to the thing in the OP.
Dammit! I was just coming here to post that. :mad:
Well, here’s my link anyway. Automated License Plate Recognition | International Association of Chiefs of Police
It would be ironic if that’s what it is.
So the OP took a picture of someone who was violating everyone’s privacy. Karma.
Which makes post #2 mightily ironic, if that’s indeed what they are.
And what about if you just took a photo of a woman walking down the street while wearing a skirt? Is that an invasion of privacy too?
[In the U.S., no. You have no reasonable expectation of privacy in public.]
Yup, looks like he sold his Del Sol to the devil.
One of the companies making automated license plate readers is a division of 3M. So it’s possible that what the OP saw was one of the engineers testing the equipment?
It certainly isn’t a standard-issue police cruiser. Even unmarked cars usually have emergency lights visible in the rear window.
Generally true, if not for commercial use.
They look very much like license plate scanners to me.
They aren’t just used by law enforcement. He may be a repo man or private detective, technologist, or whatever. It isn’t a violation of privacy to take photos of things you see in public.