The collision occurred on the A4 dual carriageway eastbound (towards Belfast) on Friday, July 29 at approximately 10.20pm.
Police say it took place just before the off-ramp towards the Stangmore roundabout.
They are asking for anyone who can help with their inquiries to come forward.
“Were you travelling on the road at this time? Do you have a dashcam? Did you stop at the scene? Did you see these vehicles before the collision?” asked a PSNI spokesperson.
“If you have any information to provide, no matter how small, please contact police on 101 quoting reference number 2037 of 29/07/22.”