The man was heading into France from Spain when customs officers in Perthus searched his car at the Spanish border, police announced on Friday.
The motorist, a 31-year-old from Hungary, denied that he any more than €10,000 in cash, which is the maximum amount that travellers can legally have when coming into or leaving France.
The border security decided, however, to carry out a search on the vehicle where they found wads of cash in a secret compartment near the brake lights. They found even more money in the area where the spare tyre is usually kept.
In total, the officers found €1,918,460 - the vast majority of which were 20- and 50-euro notes.
The Hungarian was taken into custody on Saturday afternoon on charges of failing to declare the cash and money laundering.