FBI uses essentially the same as everyone else, with just different channels and encoders, which is stuff you wouldn't see. They opt for small control heads that fit under the dash, or in the glove box or console where they won't be so noticible to a casual observer.
FBI vehicles are not always what you think in terms of police car. SUV's, vans, sedans, crossovers, pickups, what ever they think will blend in.
Unlike me, who drives a dark metallic grey plain jane '09 Impala, black walls and a prisoner gage.
MiB, thas how we roll...................
G