Can i use a Sierra 1.8td as a donor for my locost, or does it have to be a petrol car for the SVA and other tests??? The car wil have a zetec 1.8 engine when finished.

The SVA is about the safety and build quality of the vehicle, but also covers emissions. As long as it passes the emission criteria, you can power it with whatever fuel you want.
I have an SVA manual at home so I can look it up if you want .. .
Drop me a U2U, or if someone has it to hand, could they confirm.. .