The correct answer is, "Continue through the tunnel if you can." The main dangers in a tunnel fire are suffocation and smoke. If you can do so safely it’s better to drive a burning vehicle out of a tunnel. If you can’t do this, pull over, switch off the engine, use hazard warning lights and phone immediately for help. It may be possible to put out a small fire but if it seems large do NOT tackle it! But I find it difficult to understand. What if the engine explode while you continue driving through the tunnel? Very confusing.