Many times I see a great model railroad scene marred by bad vehicles. Some of us slave over our freight roster only to have the vehicles on our layout sorely detract from them. Cars and trucks are really worth our close attention as well. They can make or really break a scene.
Here are a few of my higher quality “foreground” models. I have rougher vehicles I can park in the background.
This scene would not be nearly as good if I had low-quality models with no rear view mirrors, license plates or wrong era cars. All of these cars are late-1960s to mid-1970s models which fits my era of mid to late-1970s (1975 and 1979) very well. I have a dual era layout. (Those damn yellow dots! As appropriate, I only put the wheel inspection dots and newer COTS on just one side of my freight cars.)
Your tractors need license plates too. Don’t want them to get stopped on the road!
Noone can look at my layout and think it is modern.
These cars scream out 1970s! Which is exactly what I want.
Cars and trucks need to be carefully weathered as well.
I apply a very thin wash of grimy black and roof brown thinned with alcohol with occasional dips of the brush in rust and black powder.
Attention to detail on your cars and trucks will pay off as you photograph your layout. You want them adding to the scene and era versus being a distraction.