Officers searching for Patryk Lipinski have released new images after he was last seen at a filling station in Grangemouth at around 1.15am on Sunday.
Since then, the 21-year old is believed to have travelled to Ballachulish after his car, a red Hyundai i20, was found in the area just hours later.
He is believed to have travelled to the Highlands from his home in Bathgate via the M90, A85 and A82 between 1.20am and 3.50am on Sunday, 5 September.
Officers say as time goes on they are becoming “increasingly concerned” for Mr Lipinski.
Major searches have been run as coastguard crews, mountain rescue teams, police officers and fire personnel have joined forces in the search for the West Lothian man.
He is described as being around 6ft 2in in height, of slim build with blonde hair.
When last seen he was wearing glasses, a blue t-shirt, jeans and dark trainers and was driving his red Hyundai i20, registration SA10 KNM.
Inspector Nick Hough said: “As time goes on we are becoming increasingly concerned for Patryk.
“We believe he drove from Bathgate but it is very unlike him to be out of contact with friends and family for this length of time.
“We are appealing to anyone who may have been in the Ballachulish area at these times and has seen anything which may help our searches to please get in touch.
“We are particularly keen to speak to anyone who has dashcam footage or who saw the vehicle near the Glencoe and Ballachulish area.”
Anyone with any information is asked to contact 101 quoting incident 0799 of 5 September.