Makes it a lot harder to speed -- especially with their new low-profile light bars.
The explanation in the window (picture DSCF0162) is great; I guess the officers must receive a lot of questions about it.
Prior to the rise in SUV popularity, many of the officers drove Monte Carlo SSs, Regal Grand Nationals, and Grand Prixs. The next wave was Mustangs and Camaros. Now, I'd say the 4Runner is one of the more popular models, along with the Ford Explorer.
I've also seen Toyota Avalons, Nissan Altimas (I saw a 2007 model the other day), and the G35 sedan you saw. If you see a cellular-like antenna in the rear window (for sedans) or on the driver's side rear-most window (for SUVs), it's probably an officer's vehicle.
My office is right outside a courthouse, so I often see officers' vehicles parked outside when they are in court. It's not uncommon for at least half the vehicles parked to be 4Runners (3rd and 4th generations).