When assessing the price of a CNG engine, you must look beyond the sticker price and evaluate displacement (L), rated power (kW/HP), and maximum torque (N.m). High-performance engines often utilize Electronic Control Units (ECU) from reputable brands like Bosch or Woodward to ensure precise fuel injection. Additionally, verify if the engine is a dedicated CNG design or a converted diesel/gasoline engine, as dedicated units offer superior thermal efficiency and a longer service life, justifying a higher initial investment.