I never heard about diesel inefficiency. Infact diesel engines were always fuel efficient due to their working based on high compression based ignition and direct fuel injection system. They don't use spark plugs to ignite the air-fuel mixture. The idea of gasoline GDI engine is inspired from diesel technology.
Maybe we Pakistanis have seen bigger diesel engines and think they are not fuel efficient.
Pros of diesel engines are fuel efficiency, and low end torque which means it has powerful acceleration from standstill or when you are driving at low rpms. Gasoline engines give good torque at high rpms.
Cons of diesel are noise, vibration, difficult to start in cold weather, poor emissions (remember VW scandal). Some manufacturers use glowplugs in the combustion chamber to preheat it to solve the cold start problem.
There's a reason Europeans love diesel engines and manual tramissions. They have lots of hilly terrains. Since diesel have better low end torque and manual transmission give better power transfer to wheels. USA have almost moved to automatics. You cannot find any manual vehicle there but majority of europeans are still using manuals.
https://carfromjapan.com/article/industry-knowledge/percentage-of-manual-cars-in-europe/
