Their game is probably using metric units like the German PS, the Italian cv or the French ch.
144 bhp = 146 PS but there's probably some rounding off being done - 144.45 bhp = 146.51 PS.
According to Kudosprime the N100 Mini has up to 145 bhp with a full power upgrade ( 633 mileage points ).
145 bhp is roughly 147 PS.
Guess the power upgrade ( on the car's settings page ) is what you are looking for .