Officers were called to the scene of a one-vehicle collision, in Hackmans Lane in the village of Purleigh, shortly after 2.30am on January 6.
A man in his 20s was pronounced dead at the scene and his family have been informed.
A second man, also aged in his 20s from Brentwood, was arrested on suspicion of causing death by dangerous driving and driving whilst unfit through drink or drugs.
He has been released under investigation while police enquiries continue.
The road has been reopened to traffic after being shut yesterday.
Detectives investigating the fatal collision are now appealing for witnesses or anyone with any information to come forward.
You can let the police know by submitting a report on the Essex Police website or by using its online Live Chat service which is available 24 hours-a-day, seven days-a-week.
Please cite reference 42/2246/25.
It can be found at the bottom right of the homepage at www.essex.police.uk.
Alternatively, you can call the police on 101.
