I don't know how vehicle replacement works in the FBI, but in my agency (and in most others), we go through GSA Fleet. The vast majority of the offerings there are US- made and/or from the big US companies like Ford, Chevy etc. In recent years, some "imports" have crept in. The last time I ordered a new truck, the Nissan Titan was available, as was a Tacoma. We not only have price limits, but can only buy a vehicle above the base trim if there's a mission-necessary accessory that doesn't come with that trim. I.e. I managed to get an F150 XLT (instead of XL) because I needed a towing package and a block heater.
That said, I wouldn't want to be the supervisor who has to explain why I allowed my agent to buy a "luxury" SUV. We've had people complain simply because an employee got a vehicle that had Bluetooth (came with a needed package). So I think there would be a s***storm with the general public if rank and file employees were buying Landcruisers.
If the FBI was driving LC's, they were probably seized vehicles or - as mentioned by others - gotten from overseas postings or transferred from other agencies.
