Hyundai HB20 fitted with a 3-cyl 1.0L engine...
Also available with a sedan body (still available with the 3-pot)
Volkswagen Fox BlueMotion
Altough the base engine for the Fox was a 4-cyl 1.0L, the earlier BlueMotions used the 1.6L one. Current version uses a 3-cyl 1.0L.
Subaru Vivio, with a 660cc 3-cyl engine.
This one doesn't require an introduction...
Early Brazilian Opel Corsa B with mismatching hubcaps
Instead of the 3-cyl engine used in the entry-level versions of its European equivalent, the Brazilian version had only 4-cylinder engines...
Suzuki Jimny
Agrale 1600D, fitted with a 2.9L 3-cyl Diesel (67hp)