You are talking about RED diesel type fuels.
If you run these in your car then I would not at all be worrried about engine damage. Get caught and you will have a ringside seat as your car is crushed!
And before you say they can't do that, oh yes they can. The least you will suffer is vehicle redemption and storage costs plus additional court costs and fines.
It would be cheaper to let the car be crushed in the long run.
Anyway, your choice.
I will add however if you are using you car purely off road where no vehicle tax and insurance is required then you can put whatever you like in the tank. So for track days, off roading etc as long as you trailer your car to the events then there is no problem. If you are competing in a RACMSA / similar regulated event then fuel usage will be regulated by the governing sport rules.
Moving on a little further modern 2010/2012 agricultural type vehicles will demand/require decent fuels and there is no real/basic difference between public, agricultural, restricted diesel fuels. The only real difference is in the fuel staining/colouring.
The fuels are basically the same appart from the tax/duty concession they attract.