Nah, i run my car and vans on marine diesel [33p a litre or around that mark] and i dont pay for it. We've got our own underground tanks at the boatyard i work. Compared to a boats fuel tank, im hardly using any of it!

But i dont think i'll be able to do it for much longer coz customs have caught on [almost ALL the boatyards in the area use marine diesel for the vans] so customs want to start dying marine diesel white. Much like agricultural diesel is dyed red.

The only differnce between normal city diesel and marine is the slight differnce in viscosity and colour [and tax]

I have made my own bio diesel before though, but it's too much hassel lol! I'm too lazy!