** Online used-car retailer Carvana's CVNA.N shares rise 1.3% to $461.06 premarket
** Argus Research starts with "buy" rating
** Brokerage sets PT at $500, implying an upside of 9.7% to stock's last close
** Brokerage says co "has competitive advantages over traditional dealerships in vehicle selection, price, quality and user experience"
** Average rating of 27 analysts is "buy," their median PT is $450 - data compiled by LSEG
** Up to last close, stock has more than doubled this year
(Reporting by Anhata Rooprai in Bengaluru)
((Anhata.Rooprai@thomsonreuters.com))