The mishap occurred at around 4.45 AM at Amberpet toll gate on the ORR when the victims - Sivakrishna, Sasidhar, Srikant and Raju - were returning from airport in the car after seeing off their friend Bhaskar, a police official said.
The fire appeared to have spread rapidly and the bodies were totally burnt, he said.
The five friends had started off from Hanamkonda in Warangal to the airport at around 11 PM last night.
A case under IPC section 304-A (causing death negligence) has been registered, he added.