Are you allowed in this situation to overtake the vehicle?

Why?

You may overtake the red car using the left lane, which is separated by a broken line. A car appearing in your mirror does not itself prevent overtaking, but you must check that its driver has not already started overtaking you. When changing lanes, give way to vehicles already travelling in the lane you intend to enter.

art. 24 ust. 1 pkt 2 oraz art. 22 ust. 4 Prawa o ruchu drogowym