Whoever is facing the same question buys the Brodit 511 307 (6-10mm thickness) as fits the Nexus 5 without envelope, Car etc. outstanding.
In holder to 13 mm it wobbles because the depth of 13 mm can not be reduced.
For details on the Brodit holders is already in the other reviews.
Yes, it is expensive but the holder Qualitatively really good.
Have fun with it
Supplement January 2014:
Now have the original Google Cover (yellow) and also so that the Nexus 5 fits perfectly into the Brodit holders.