Some years ago I purchased some Diecast Model Cars from Lledo in 1:60. I intended to use one as a carwreck with some rubble to go with my ruins.
This in mind I took a hammer and deformed the roof with some strikes. Then I glued some wall pieces (crushed Cast of a Wall), some gravel and sand on top and around the stern of the car.
After priming the whole piece in dark grey I airbrushed the car body in black. The details had been painted with silver (buffer-bar), white (parts of the tires) and in light blue-grey (headlamps). The car body was sealed with two coats of gloss varnish to get the impression of lacquer.
The wall pieces got a dark reddish brown and the sand a dark brown groundcolor. In a next step this parts were drybrushed in dark red and different shades of ocher. The dusty effekt, both on the car and on the rubble, had been acchieved by the use of different shades of dry pigments.
At last I added some smal cutoffs from overhead transparencys with superglue to represent the broken panes (best seen on the third detail shot).
Here comes some detail shots of the finished piece. The 28 mm German Grenadier is from Black Tree Design and is shown for scale.
Hopefully I could give you some inspirations.