Not possible. Regular Audi radios are not like some aftermarket units running Windows CE or Android that can use external application from SD card. Also in proper MMI unit SD card is only used to update maps or firmware, but all supporting hardware is already in place... Frankly speaking I'm surprised with you dealer statement... I'd rather vote for possibility to use SD for maps upgrades on Q3 as well, but I do not know this new system in details.