I have LPG fitted to my last four surveillance vehicles. The current one has cost me just on $5000 for a dual 65 ltr tank, it is registered under the company so I don't qualify for the rebate, its up to my accountant to work out the depreciation as that is what I pay him for. I have been very happy with all vehicles and I just fill up and go. I don't worry about the calculation and differences as long as I have a reliable comfortable vehicle, it will earn me dollars and pay for itself.