A 16-year-old student with a liking for limousines was arrested in Richmond after illegally lining up a luxury car to take him and two female friends for a spin, police said. Sgt. Robert Flores said a reservations clerk at Executive Limousine Service in Walnut Creek got suspicious earlier last week about a caller who sounded as if he were trying to disguise his voice so as to sound older. Shannon Vaimoana said the caller asked for a stretch limousine to drive up in front of Richmond High School on Wednesday, with the driver holding a sign reading "Happy Birthday." Police said the personal check provided for the $600 rental had been stolen through the mail. Flores, pretending to be training for a chauffeur's job, sat next to the driver when he went to the school to pick up the three students.