When sourcing a hydraulic car lift, you must prioritize lifting capacity (typically ranging from 3,500kg to 5,000kg for passenger vehicles) and lifting height (standard is around 1,800mm-2,000mm). Ensure the motor power is sufficient (usually 2.2kW to 3.0kW) and check the cylinder quality, specifically looking for high-quality seals to prevent oil leakage. Additionally, verify the steel thickness of the columns; for a 4-ton lift, a thickness of at least 5mm to 6mm is recommended for structural integrity.