Tara Reid, 25, testified before a New York grand jury hearing as part of a legal case that has kept the Hamptons buzzing all summer: that of publicist Lizzie Grubman, 30, who stands accused of intentionally backing her SUV into a crowd of people outside Southampton’s trendy Conscience Point Inn. Reid reportedly was at the same party as Grubman at the Southampton home of designer Alex Von Furstenberg on July 7, the night of the crash. Sixteen people suffered injuries ranging from cuts and bruises to broken bones. “She is happy that it is over,” the “American Pie” and “Josie and the Pussycats” actress’ publicist said of Reid’s testimony. “It was very taxing.” The rep did not reveal what Reid said on Tuesday, but insisted that Grubman and Reid “are very good friends.” Reid was one of several witnesses who have been called to testify before the grand jury, which convened last week. Grubman, whose client roster includes Britney Spears and Jay-Z, is accused of intentionally plowing backward into a group of people after she had a heated argument with a bouncer. Earlier in the evening, Grubman reportedly went into a tirade when the bouncer told her to move her Mercedes-Benz SUV, which was parked in a fire zone. (The vehicle actually belonged to her father, entertainment attorney Allen Grubman. Both Grubmans are being sued by some of the alleged victims for several millions of dollars.) Lizzie Grubman was charged with assault, leaving the scene of an accident and reckless endangerment. She is currently free on $25,000 bail and has apologized for the crash, which she called an accident.