IIRC, engineers do have a yellow text that appears on their counter when they encounter mines. The game engine automatically sets them to clearing the mines so you can choose to leave them in the hex to do so.
Now, if you are running them around in trucks, you will not get mine attacks, but neither will you mark those hexes a mined. Stay in the trucks and the mines will not be cleared. The hexes you passed through to discover mines will still appear normal on the map not revealing the hidden mines. Not a bad trade off for a free pass in trucks for the engineers, IMHO.
BTW, your engineers sitting those trucks are now isolated in the opponent's turn and very vulnerable to destruction. I hope this debunks the myth that running through minefields in trucks is a good thing to do with your engineers. Minefields are only useful if covered by firepower.
Go ahead. Run engineers through my Soviet minefields in trucks in a PBEM game. Be sure you have lots of stationary to write those letters that start...
Dear Mr & Mrs So and so,
We regret to inform you....
I know where the wooden crosses grow.
Dog Soldier
Fast is fine, but accuracy is everything.
- Wyatt Earp