Literally 'lead and lift' - the thing that drives movement. This is actually a phonetic transliteration of 'engine' that also conveys the meaning nicely.
In everyday Chinese, 发动机 is more common for car engines, while 引擎 is preferred in tech contexts (搜索引擎, search engine) and when talking about engines figuratively (经济增长引擎, engine of economic growth).
