A hydraulic brake system (50) for a vehicle such as a golf car or the like uses the same brakes (52) and same brake pedal (80) for both service braking and park and hold braking. The brakes (52) are selectively engaged, locked in their engaged position, and released using an integrated control assembly including a brake pedal (80), an accelerator pedal (82), and a brake pedal locking mechanism (84). The brake pedal locking mechanism (84) is configured to automatically latch the brake pedal (80) in a locked position thereof and to automatically unlatch the brake pedal (80) from its locked position upon either subsequent movement of the brake pedal (80) into an overtravel position or subsequent actuation of the accelerator pedal (82). In addition, a hydraulic accumulator (62) stores part of the energy generated upon brake pedal depression and consequent manual actuation of a master cylinder (60) of the system to maintain the brakes (52) in their fully engaged state when the brake pedal (80) is latched. The stored energy can also be used to help return an applied brake pedal (80) to its released position, in which case return fluid flow to the master cylinder (60) is damped to avoid undesirable severe kickback of the brake pedal. The accumulator (62) preferably comprises a modular spring and retainer assembly that can be preassembled separately from the remainder of the system and subsequently mounted on the system as a unit.