I've seen the number of induction coils increase drastically over the years in The Netherlands. They are quite easily recognizable, as there's typically a solar panel on a pole, that appears to provide power to the system.
Considering there's a wide variety of vehicles on the road, surely each variant must have (slightly) different characteristics when passing over the coil; especially when in a specific place at a specific time.
And given that they are situated at highway exits (see picture) or after entrances, and road users unable to exit and enter elsewhere, it would be trivial to track the bulk of a vehicle's trip.
This in context of ALPRs (in different forms) being in place at strategical locations (large junctions or at bridges or tunnels, and parking), and the address of vehicle's owner; you'd be able to connect the dots, and end up with a pretty complete picture.
The readings will have an extremely low signal to noise ratio, at best you coils differentiate a truck from car by length of the pulse, but with speed already being ±30% variability any small difference in cars inherent properties (size in length or amount of metal) would quickly be reduced to nothing. Then for every make and model you have thousands of cars already, I don't see how you could possibly differentiate between those even in theory.