Mötley Crüe frontman Vince Neil didn't just fail three field sobriety tests during his June DUI bust -- he failed epically ... with a blood alcohol level almost three times the legal limit, according to police.
TMZ obtained the Las Vegas PD report, which says Neil was pulled over for doing 60 mph in a 45 mph zone and for "weaving between the lanes."
According to the report, Vince reeked of booze, copped to swilling three glasses of bubbly and flunked three field sobriety tests. Cops claim he eventually gave up by saying, "I can't do this."
Vince was able to blow -- for two breathalyzer tests -- and according to the report he registered .215 and .216 ... well over the .08 limit.
Neil has since been charged with DUI and speeding -- and is set to be arraigned on September 27.