The 7.62x54mm is actually a more powerful round than the 7.62x51mm round we know more commonly as the .308.

The big Russian round is in the power range of the .30-06 round, and its 3 clean passthrough shots demonstrate this pretty conclusively.

In fact, with any of the rifle rounds life inside the passenger compartment would be very short and very unpleasant, which you can see by looking at this seat.

There were bullet fragments and bits of metal EVERYWHERE in the passenger compartments after the rifle/door shots, and there was still enough oomph to penetrate the door completely and make life short and bloody for anyone hiding on the other side of that car.

Lessons learned:
Car doors offer absolutely NO reliable cover from rifle rounds.

Remember that these are 3 round strings being fired at a liesurely pace into the car doors. Someone who meant business could make swiss cheese out of those doors and anyone in front of OR behind them in no time flat.