Small styling changes and a new engine changed the Type 172 BC into the Type 172 R in 1926. The engine was a 720 cc I4 and produced the same power rating as before, but torque was quoted appreciably higher. In 1928, the engine was replaced with a smaller 695 cc powerplant that nevertheless produced more power, at 14 horsepower (10 kW). A smaller engine and a wider track nevertheless lowered the rating of the new Type 172 M tax classification to 4CV.
Total production of the Type 172 models in this timeframe amounted to 48,285 units.