permanent GPS track recording

We have gps tracking on our ambulance fleet. Records and maps our travels and data is stored on our servers for at least a year. It pinpoints location and speed every minute. They are not fool proof and are high maintenance. Our system, wish I knew the name of the new program, plugs into the obd2 port under the dash and reports all vehicle functions and engine codes. The biggest fault with the system is the call from the boss..."why are you doing 400mph?". Of course he knows we're not, but we can get moments of gps satellite error showing grossly exaggerated speed and location. Allot of the errors occurred overnight while the ambulance is parked. Our location can be reported by as much as 25 miles away at speeds in excess of 100mph. We of course have vehicle data now being recorded to dispute those reports. There is no gps based product out there in civilian hands that can be held as absolutely reliable for location tracking history. This has been a 5 year project for our company with combination cellular/gps live tracking. The vehicle data is a huge bonus for us as a vehicle can have a miss and shutdown and that moment and code is instantaneously sent to the database if we are in cellular coverage.