I'm surprised it still not been added yet as a feature especially now that we can create custom challenges, but I'd love to use the various vehicle skins in challenge mode.
Yeh same here, not to mention that we can't use all the vehicle skins for different Era building styles. For example the Clean '93 JP Jeep in the 2015 JW Ranger Station or the Malta Truck in the Jurassic Park Ranger Station, etc.
I really hope we can use the other vehicle skins in custom challenge mode. Using the same default skin option is fine but it makes the driving experience a less personal one.