Why does the old Jetta have small displacement but strong power?

[MacHarrison]

The old Jetta uses a diesel engine, which has the advantage of small displacement but strong power. In terms of power and torque: Diesel engines focus more on vehicle torque, with relatively long cylinder strokes, which can reduce engine speed and better amplify torque. In terms of fuel: Diesel engines have a thermal efficiency conversion rate of at least 35% or higher. Manufacturing costs: The cylinder block and cylinder head of diesel engines are thicker and more robust, with stronger pressure resistance. Components such as pistons, connecting rods, and valves inside the cylinder require higher strength for support, resulting in slightly higher manufacturing costs.