You can find Sixt special rates here: Sonderangebote – Autovermietung Sixt
Mercedes-Benz AMG C63 rate is 299 eur per day including 250 km.
Bookable from April until end of October.
Available from following Sixt stations in Germany:
Munich Airport (MUC)
Munich Schwabing Luxury Cars – Anni-Albers-Strasse 11, 80807 München
Cologne / Koln Luxury Cars – Marzellenstr. 13-17, 50668 Köln
Dusseldorf Luxury Cars – Koenigsallee 59, 40215 Düsseldorf
Frankfurt Westin Hotel – Konrad-Adenauer-Str. 5-7, 60313 Frankfurt am Main
Berlin Adlon Hotel – Unter den Linden 77, 10117 Berlin
Reserve your AMG C63 here: http://www.sixt.de/php/reservation/topoffer_details/f/de-amg-de
Munich Schwabing Luxury Cars has also Mercedes-Benz AMG CL63 in their fleet.
