Minimum ceiling height wants to be 4m if you are having a 2 post lift for a regular car and 4.5m for a 4x4 etc. One option is to have a 1m to 1.5m pit running between the legs of the 2 poster so you can get away with a lower ceiling height
I also recommend using self levelling Agilia concrete to cast your base. It costs a bit more but its the bollocks [/quote]

Good idea about pit.I actually need to raise the garage up by about 1.5m so that would be perfect.