Fraudsters are trying to con motorists out of cash on the M62 by claiming they have broken down.
West Yorkshire Police has issued a warning to drivers using the motorway after a spate of incidents.
The crooks flag down passing cars before telling would-be victims they have run out of petrol and need to borrow cash.
In the latest incident, on Sunday, a man was reported to be trying to swap cheap jewellery for money at Ainley Top services near Huddersfield.
Insp Christopher Norbury said: “The latest incident echoes what we have seen across the motorway network in the last few weeks involving jewellery been offered in exchange for cash after people claim to have run out of petrol or encountered some form of emergency on the hard shoulder.”
Another similar incident was reported at junction 28 for Leeds, where an Eastern European man was flagging cars down after claiming his bank card had broken and he needed £20 to buy petrol. The same thing happened near junction 24.
Insp Norbury added: “Our advice is not to stop and leave it to the police and our partners to deal with.”