Apparently early carb VWs had no swirl pot in tank. So when converting from carbs to FI, owners would try and add a swirl pot. Not wanting to replace the tank, they added one externally. Some later VWs had external "cache tanks" which served same purpose and could be retrofitted to earlier models.

Warm recycle fuel needs to be cooled and mixed. Given that Porsche used a swirl pot, you would think VW would have done same on their FI engines?

Like almost everyone, I once owned a Beetle and my daughter an early Golf. But I paid no attention to them! Not my favorite cars!

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Graham
85 300D,72 350SL, 98 E320, Outback 2.5