Merci Robin. Erreur de ma part, je les assimilais plutôt aux buildings.
Voici un thread sur le sujet sur GS :
https://www.gamesquad.com/forums/index.php?threads/b32-5-rail-cars-differences-from-buildings.198340/En fait, à l'origine, les concepteurs avaient voulu faire des railcars un dérivé de wooden buildings, mais ils ont décidé d'en faire un terrain indépendant (mais en bien des points comparable).
La footnote 16A du chapitre B l'explique, et liste les différences :
We thought about using the rules for wooden buildings as the basis for the Rail Car rules but felt there were too many differences between the rules for that to work, e.g., Rail Cars are not a Rout destination (A10.51), provide no Rally Terrain Bonus (A10.61), are not buildings for Victory Conditions, and incur no Desperation penalty (C13.81) for firing “backblast” weapons from them; Mortars may set up in and fire from them, all Fortifications allowed in a GLRR hex (32.11) may set up in them, and the Kindling and Spreading Fire #s are different, as is the Sighting TC DRM.
Donc la confusion est assez facile à faire.