I'm looking to rent a 2005 or 2006 Saab 9-3 in or near Stuttgart,
Germany in May.  I have not been able to find a place that rents
Saabs.  Where can I find one that is no more than two hours drive from
Stuttgart?

Dear rleale_intrepid, 

This model is considered exotic and rare in Germany, and therefore, it
is usually not offered for rental.

One option to rent it within a 2-hour drive distance from Stuttgart is
in Switzerland, where the model is offered for rental. Large rental
companies also offer chauffer services and services to return the car
in another station, for an extra pay.

Avis-Switzerland offer the Saab 9-3 as part of their "Group H" cars: 

Avis Switzerland - Group H
<http://www.avis.ch/avisonline/fleet.nsf/ShowCarDescription/?Readform&Country=CH0&Lng=GB&Ctr=CH&GRPList=~A~B~C~D~E~F~G~H~J~K~L~M~P~N~O&ViewType=ShowFleetIntl&GRP=H>

Avis Switzerland - Homepage
<http://www.avis.ch/avisonline/ch-gb/avis.nsf/fTopFrameSets/B47A5C88DF53E4BDC1256CEC004F2505/?OpenDocument&~Default>

The station in Schaffhausen is, according to Via Michelin, 1 Hour, 38
minutes away from Stuttgart:

Via Michelin
<http://www.viamichelin.com/viamichelin/gbr/dyn/controller/ItiWGPerformPage?reinit=1&strStartAddress=&strStartCP=&strStartCity=schaffhausen&strStartCityCountry=185&strDestAddress=&strDestCP=&strDestCity=stuttgart&strDestCityCountry=240&image.x=15&image.y=5>

(There are also stations in Basel, which is also not far away from Stuttgart). 

I'm afraid I couldn't find any rental companies in Germany that offer
this vehicle.

I hope this answers your question. Please contact me if you need any
clarification on this answer before you rate it. My search terms:
["Saab 9-3" autovermietung baden wuerttemberg]
[hertz saab 9 3,]
[ Europcar saab 9 3]
["Saab 9-3" autovermietung strassburg], 
[saab stuttgart]
[Saab 9-3 autovermietung]

This is exactly what I was looking for.  Thank you.