James McDonald, 23, was last seen at home on Monday, September 28, say police.
Although he has family ties in the Garstang area, officers investigating his disappearance say they believe he has driven to London in his silver Ford Fiesta.
Police say they believe this to be the case after they checked the vehicle's records and found that his car has since been sold in London.
His family's concern for his welfare prompted them to report the 23-year-old missing on Sunday, October 11.
A police spokesman said: "We are concerned regarding the whereabouts of James McDonald, 23 years of age, who has been missing from his family since September 28 at his home address in Preston.
"He does have family ties in the Garstang area.
"But we believe he may have travelled as far as London but have little information beyond there. He has travelled in his Silver Ford Fiesta which we believe was sold in London.
"We would urge anyone who has seen or spoken with James or knows where he may be to contact Lancashire Police on 101 quoting log reference LC-20201011-1686."