No EU country charges any foreign national vehicle differently for driving its highways. This is tantamount to “Highway Robbery”.
I am a regular tourist in a Spanish-registered car with a Via Verde transponder for Portuguese highways. My SUV car model is rated as Class 1, but Via Verde charge it as Class 2 – a bus! The tariff is about double that of Class 1.
Via Verde explained to me in person that it is their practice to “Charge double for foreign registered cars” compared to a Portuguese car. I argued this is in contravention of EU laws on Fundamental Rights. The response was a pleasant shoulder shrug; the short-necked syndrome, I call it.
I have formulated an official complaint enlisting the FRA (EU Fundamental Rights Agency) into pressurising Via Verde to conform, maybe with a fine.
Name and address withheld