Generally speaking, the police do not transport male and female arrestees or inmates in the same vehicle. There is a good reason. According to a recent article from the Green Bay Press Gazette, a male and female suspect who had been arrested separately for drunk driving were put in the back of the same police car to take them to the station.
While being transported, the couple started having sex in the back of the police cruiser. The officer immediately ordered the male DUI suspect to pull up his pants and placed him in the front of the police car.
When they arrived at the station, both were charged with lewd and lascivious behavior in addition to driving under the influence of alcohol.