The driver, who claimed to be German, asked passers-by for money on the A1(M) near Sherburn-in-Elmet, after signalling them to stop.
The alarm was raised by one victim who tried to speak to the driver in German, which he failed to understand.
Police say they have a photograph of the suspect and are trying to trace him.
A police post on Facebook said: “It is highly likely this is a scam. We have a photograph of the male in question and are following this up.”
Police say the alleged con is similar to an earlier fraud involving the sale of fake jewellery, for which 14 people have been arrested.