The engine itself has no braking due to the lack of the variable air-intake that gasoline engines have that would otherwise starve the engine for air especially when downshifting and closing the throttle.
Specifically on non-big-rigs, modern diesel cars and pickups create engine braking using a small turbo and tighten the spline or in some cases have an exhaust feedback baffle or flap, varies with year/model. Big rigs still use jake-brakes.
Specifically on non-big-rigs, modern diesel cars and pickups create engine braking using a small turbo and tighten the spline or in some cases have an exhaust feedback baffle or flap, varies with year/model. Big rigs still use jake-brakes.