Wow, this cake is amazing, I want to make one like this for my grandson.

How did you get the bit above the cab so good, is it gum paste? How did you get it to stay in place? 

Thanks fozzie57 - On top of the bottom cake (where the tyres are), I placed a wedge-shaped piece of polystyrene (covered in black fondant) the same size. Then with the dumper, the cakes sits on cardboard cake board, bent upwards, that extends about 2" over the end of the black fondant wedge. Then supported it all with dowel cut to size. It was tricky to do and took all day, but I was really happy with the results too. Thanks :)