There shouldn't be anything between the major brands as they all have to comply with the current Australian diesel fuel standard which for the last ten years has become more and more regulated, and tougher especially as regards sulphur content. I think the best tip is to avoid any of the budget outlets if you have them over your way. I also wouldn't use any bio-diesel mix even if BMW says 5% bio diesel is okay as that side of the fuel industry here in Australia seems less well regulated than the mainstream side.