Hi naseer
If you are going for solution based on modules, you have to consider the following things:
1. you have to make a PCB where your module is going to sit.
2. your chosen microcontroller should support the module
3. you have to take care of architecture, schematic, layout, pcb fabrication, assembly and testing on hardware side
4. Also you have to concentrate on architecture, driver devolepment and APIs, testing.
Better you go for some EVM on vehicle tracking using GPS and GSM/GPRS.. use your brain on the application side.
GM862-GPS is good one for GPS tracking.. please read the attached HUG manual. so that you may know some idea on serial communication of the module and PIC18F248.
All the best.