Marc Martin, 22, and Matt Preece, 21, died after the BMW hit a tree and flipped on to its roof in High Beeches Lane, Handcross, on 17 December.
Two other passengers, a girl aged 16 and the 20-year-old driver, were hurt. The crash happened at about 22:00 GMT.
Sussex Police said the man was being questioned on suspicion of two counts of causing death by dangerous driving.
The driver of a car involved in a single-vehicle crash in West Sussex in which two men died has been arrested.