Police are appealing for witnesses to a serious single vehicle collision on the A259 Bodyshop roundabout at Littlehampton in the early hours of Saturday (27 February).
A white Mercedes C250 travelling westbound is believed to have left the road, mounted the roundabout and hit a tree, at about 1.34am.
The driver, a 36-year-old man from Littlehampton, and his passenger aged 32, from Worthing, both sustained life threatening injuries.
They were taken by ambulance to the Royal Sussex County Hospital, Brighton.
The westbound lane of the road was closed for several hours while investigation work was carried out but has now re-opened.
PC Steve Creal said, "We would like to hear from anyone who saw the Mercedes being driven in the area before the collision or anyone who may captured what happened on dash cam."
If you can help the investigation email collision.appeal@sussex.pnn.police.uk quoting Operation Reading.
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