The invention discloses an automotive energy accumulator. The automotive energy accumulator comprises a tank body and a piston. The piston movably penetrates into an opening of the tank body. An opening of the piston faces an inner cavity of the tank body. The inner cavity of the tank body and an inner cavity of the piston form an energy accumulation space used for containing working gas together. A first guide ring, a sealing ring, an extrusion ring and a second guide ring are arranged between the outer side wall of the piston and the inner side wall of the tank body. The outer side wall of the piston is provided with a first clamping groove used for placing the first guide ring, a second clamping groove used for placing the sealing ring and the extrusion ring, and a third clamping groove used for placing the second guide ring. The first guide ring and the second guide ring are located at the two sides of the sealing ring and the extrusion ring correspondingly. The first guide ring gets close to the opening of the piston. The sealing ring gets close to the first guide ring. The extrusion ring gets close to the second guide ring. By the adoption of the automotive energy accumulator, the width of the second clamping groove is increased, the extrusion ring is additionally arranged in the second clamping groove, and hydraulic oil which cannot be cleaned up on the guide ring can achieve secondary removing.