Odell Beckham Jr.: I May Rep Buick ... But I Drive a Ferrari!

Don't believe everything you see in commercials ... 'cause when Odell Beckham Jr. whips around in Bev Hills, he ain't driving a Buick -- he's in a $300,000 Ferrari.

The NY Giants superstar was doing some shopping on Rodeo Drive Thursday -- and while he wasn't doing much talking, he was definitely flossin' in a big way.

Check out (what appears to be) a Ferrari F12Berlinetta -- which rocks a 6.3-liter V-12 engine and goes from 0 to 60 in 3.1 seconds. The price tag is reportedly somewhere in the $325k range.

FYI -- OBJ is still in his rookie contract with the Giants and is only expected to make roughly $3 mil this year ... unless he strikes a new deal with the team before the season starts.

Meantime, keep gettin' that Buick money!