What we have here is not a sneaky clever spying plot. What we have here is a sneaky little fee, hidden in the fine print. It's a hidden price increase, a classic scam.
Why did they fine the man $450? Because that's all he had in his bank account. Had there been more in the account, they would have taken more.
Our plaintiff walked into some generic car rental shop (called ACME, no doubt because the owners were too stupid to actually come up with a decent name for their business), asked how much it would cost to rent a car, and found the price was acceptible. He was handed a contract. An intelligent, rationally paranoid person would have read the agreement carefully, torn it into little pieces, thrown it at the offerer of said contract's face, and cursed him for being a lying cheating git, finally storming out to the sound of the clerk's pathetic sniveling of "I just work here, I don't make the rules!".
What's wrong with the contract? Well, it exposed Mr. Plaintiff here to an OPEN-ENDED UNLIMITED LIABILITY! Anybody who signs such a thing without being coerced is a fool. Shit, I think ACME was extra nice to the guy, considering what he agreed to. Suppose that he had driven at 80 mph for an hour on an open highway, which is not an unreasonable speed or necessarily even something that will annoy the police. He'd pay $150 * (60 minutes / 2 minutes) = $4500. It's their word against his whether he drove such a speed or not, and they have the Magic Scientific GPS Machine to back them up in court. Suppose that he drove for 10 hours at such a speed. Talk about easy money - hey, they could let him keep the damned car and still walk away ahead.
ACME had no intention here that ANYBODY would actually obey the speed limit specified on the agreement. They deliberately placed this provision into the contract so that they could levy enormous charges on the renter which had not been made clear to him before he rented the car. All their reasons about "stolen cars" and "safety" are a big pile of hooey. This is just a scam like any other.
Even if you do start seeing GPS machines mounted in rental cars for the purpose of tracking them, no reputable company is going to go around doing this. They wouldn't be reputable very long! I really doubt that anybody rents from this dipshit little ACME outfit twice, but a big nationwide chain like Hertz needs repeat business. This is just a classic con-game, raising the price after the mark has already agreed.
If the plaintiff has a case at all, it won't be for privacy invasion. It will be for fraud.