At what maximum speed limit can you drive a passenger car of maximum permissible weight 3 t, on a single-carriage expressway?

Why?

The blue D-7 sign identifies an expressway. On the single-carriageway expressway described in the question, a passenger car without a trailer may travel at up to 100 km/h unless signs impose a lower limit. The 120 km/h limit applies to dual-carriageway expressways, while 90 km/h is the general limit on ordinary single-carriageway roads outside built-up areas.

art. 20 ust. 3 pkt 1 lit. c Prawa o ruchu drogowym; znak D-7 „droga ekspresowa”