1600 (Neue Klasse) 1964 to 1968

The 1600, introduced in 1964, used the pistons from the 1800 to enlarge the 1500’s engine to 1.6 L (1573 cc) and 85 hp (63 kW). It replaced that smaller model in 1964 and was produced through 1968. 

1964 BMW 1600 Specifications

(Source)