No one talks about suspension or engine efficiency of the leather on the seats any more.

Some airlines have exchanged large bottles of spirits for medium-sized ones, and others are washing engines to remove soot deposits, which impede engine efficiency.

All petrol contains traces of tar-like heavy oils, which, over time, can clog these spray holes and reduce engine efficiency.

A special compact pentroof combustion chamber design with central spark plug location was incorporated to optimize engine efficiency.

Low-friction, roller-bearing rocker arms are used to help reduce friction and improve engine efficiency.