Roberto Merhi, driving for Persson Motorsport in the Junge Sterne Mercedes last year.

"We'd gone there to denounce the fact that, two years after its inauguration, it still hasn't opened," said Valencia regional deputy María José Salvador after a visit to Castellón airport. "When we got there we heard a noise like a Formula 1 car and we saw a vehicle doing laps of the runway."

Upon quizzing the security guard, the delegation of politicians, which included the deputy speaker of the Valencia assembly, Ángel Luna, and the mayor of nearby Vila-real, José Benlloch, were directed to the public company that runs the airport, Aerocas. Its president, Carlos Fabra, is a former Castellón provincial leader and the driving force behind the facility, which has yet to see a single plane arrive or leave.

One of the delegation, Eva Martínez, called Aerocas and was told that the car had permission to be there by an administrator who did not confirm the name of its driver. Her question was answered when a group of children arrived to catch a glimpse of Roberto Merhi, a Formula 3 champion and local resident, who now competes for Mercedes in the DTM championship.

Merhi visited Fabra in 2010 and presented him with a model of his car, which bore sponsorship from the local tourism department. Despite Martínez's failure to raise an Aerocas manager on the phone, she held little doubt as to who had authorized the session: "I'm sure it's the person who thinks the airport is his."

The delegation said that their planned complaint will not be to do with the driver's training but the lack of transparency over activities at the phantom airport, which was opened in 2011 by Fabra and former premier Francisco Camps, who resigned that year to stand trial in the Gürtel corruption case.