The show’s crew had to leave the country during filming after trouble erupted when it emerged they were using a Porsche with the registration number H982 FKL, which some people suggested could refer to the Falklands conflict of 1982.
May told Absolute Radio’s Christian O’Connell they bought the car - complete with the number plate - in the UK because it was the best available vehicle of its type and he said he had not even noticed the plate until it was mentioned online.
He said: “How could we have done it deliberately? All we’ve done is buy some second hand cars.
“It’s actually meaningless if you look at it. You have to want to see the meaning.”
The team from the BBC2 show were in South America filming a special on a remote highway passing through Chile and Argentina.
May said: “We do muck about but we weren’t going there to mock people about their war casualties.”
He said they decided to change the plate once they had finished filming on the country’s roads, but it had not been possible to do it earlier.
He said: “Go outside and change the number plate on your car and then see what happens the next time you meet a policeman. You just can’t do that.”
The programme has already run into problems this year, with one edition found to be in breach of Ofcom’s broadcasting code for the use of a racially-offensive term during a two-part special filmed in Burma, following a complaint from a viewer.
And presenter Jeremy Clarkson apologised after footage, that was never broadcast, emerged in which he appeared to use the n-word, although he denied actually saying it.