Is there a 7 seat conversion for the Audi A6 avant?

Yes, there are aftermarket 7 seat conversions available for the Audi A6 Avant. These typically involve adding a third row of seats to the rear of the vehicle, and may require modifications to the interior trim and rear suspension to accommodate the additional seating. It's important to purchase and have these installations done by a reputable source that has experience with these types of conversions. There are also legal and vehicle registration issues to consider, as adding rows of seating and changing the seating capacity of a car can affect the laws and regulations. These conversions cannot typically be done at the dealership and are considered 'custom'. Always be sure to consult your local regulations before making any permanent modifications to your vehicle.