Wiltshire Police has renewed its appeal for information following a serious collision in Collingbourne Ducis.
Emergency services were called to the A346 shortly after 10am on Sunday April 19 after a crash involving a Land Rover and a motorbike.
The motorcyclist, a man in his forties, was airlifted to hospital in Southampton, where he remains in a serious condition.
Officers are now trying to identify the driver of a blue vehicle seen in the area at the time.
Police initially believed the car to be an Audi A1, but now say it was a Volkswagen ID3.
The vehicle was travelling west along an unnamed road from Wexcombe towards the A346.
Investigators are urging the driver, or anyone with dashcam footage, to come forward.
Anyone with information is asked to contact the Serious Collision Investigation Team quoting the relevant log number.
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