Microchip MRF89XA and Anaren A1101R08A good candidates as internal RF modules for vehicle tracker.
Anaren module twice less than Microchip but less antenna. So need check in a real conditions.
But no library from STM32 processor.
After some days i port SimpliciTI and MiWi libraries to STM32 platform.
Now check both solutions for internal mesh network inside car - OBD, camera, display, sensors and control modules for vehicle tracker
Download from CodePlex
Also port Microchip TCPIP (WiFi) stack for STM32