Overall, excellent experience with the exception of billing. SIXT tried to charge me 3X the average cost of the long term rental for adding a single day. The representative who assisted me took the issue up with his manager and the company confirmed a new rate by email. Unfortunately, their main system did not reflect this rate change and, despite multiple calls with assurances from SIXT that they would refund the difference, it took forever to get any refund and this was nearly US$100 less than promised. Very disappointing (and not responsive post hiring). Never again!