These auxiliary tanks certainly are a quality bit of kit and they are designed for the job, however no one has mentioned one problem and that is that it will need filled at every fuel check as the fuel is used from this first. The filler is quite small and difficult to fill, once this is full the main tank will need topped up. - this will take at least twice as long as a normal top-up, increase the likelyhood of spillage and cause queues at the fuel stops.