A "wannabe" Bra Boy gang member and his teenage brother have been charged over the fatal stabbing of a homeless man in Maroubra in Sydney's east.

Peter Hofmann, 68, was living in his car in the beachside suburb after a string of failed investments and scams resulted in him going broke.

He refused offers of accommodation from friends and family, and instead opted to live out of his 1990's-model Ford Laser.

The retired bus driver's body was found inside his car, parked on Mons Ave, on the night of June 21. He had been stabbed a number of times.