AH by Gary Gygax: "Victorious German arms: An alternate military history of World War Two"

  Have seen it suggested that Stalingrad could have been taken quickly, on the march and possibly that's the case.  However the Germans would still have to maintain substantial forces in the region to prevent a counter attack and any advance down the west bank of the Volga, while it gives a wide river as a flank protector would mean a long defensive line and even longer logistics chain.  You might have had both army groups trying to close on Baku but that's a hell of a long way and will stretch logistics massively.  That would also make the entire force - 2 army groups or much of - vulnerable to a counter attack and could lead to and even greater disaster that OTL.

  The big issue is logistics as much as Soviet resistance.  How far can the Germans reach without major breakdown of something?

 

  Sorry, don't know how a link got established as it wasn't my intention.   Have removed it.

  Yes simply blocking access to Baku for the Soviets, especially since their other primary sources at that date were in areas already taken/threatened in the region north of the Caucasus Mts could have gravely weakened the Soviets.  Imports from the US could have made up the shortfall a bit but only really via the Trans-Siberian route and that would take capacity from somewhere else.  Possibly an advance to the Astrakhan region without trying to push to Baku, or at least close enough to enable the blocking/damage of that pipeline as well. 

  To be frank I wasn't aware of any pipelines in this period from Baku.  However have also read that the Volga was such a vital supply route - for general movement of stuff - that the relatively short period where the Germans had control over one side in the Stalingrad region caused them some significant problems.  It wouldn't have gained the Axis any additional oil in the short term at least but could have gravely weakened the Soviet ability to counter attack effectively.