a lot of people fuel or get the toll collect at the aral site on the a3 e25 at berchem, this gets busy and very full over the weekend truck ban for Germany, if you miss it come off at the junc as you come out of the second tunnel on the A13 just before the border there is a shell at schengerwiss fuel etc (no useful parking) or if you only want the toll the first layby in Germany over the river at perl is ok. dont travel without it or it gets expensive, and if they think you should have paid more a top up fine will come through the post.