Which civilian plane below has the greatest number of units produced?

The Cessna 172 is a four seat, single engine, high wing aircraft with tricycle landing gear. Measured by its longevity and popularity, the Cessna 172 is the most successful aircraft in history, with 43,000+ units built. When introduced in 1956 it cost $8700 ($78,375 in 2017 dollars).

In second place is the Piper PA-28 Cherokee. It is a four seat, low wing aircraft (introduced in 1960) designed for flight training, air taxi and personal use. 32,778+ units were produced.

The Cessna 150/152 , introduced in 1958, is a high wing, two seat aircraft designed for flight training and touring. Initial cost was $6995 for the standard model. 31,500+ units have been produced.

In fourth place is the Cessna182 introduced in 1956, with 23,237+ aircraft produced. It was designed as a light utility aircraft with wider fuselage, enlarged baggage compartment, and higher gross weight than the smaller Cessna 172.

The Cessna 172, Cessna 150/152, and Piper PA-28 have been the primary training aircraft for the past half century, which has contributed to their popularity and production numbers.