user52078: I am doing a project on Vehicle tracking and security. In my project Micro controller will sense input from sensors and at the same time it has to sense signal from user for tracking purpose and continuously checking the speed limit and boundary. so, there will be 3-4 tasks that would be executing parallel. Can anyone suggest which one is perfect for this kind of project... Arduino-Mega or Rasberry Pi? 

user7689: A RaspberryPi is essentially a small, low-spec computer. It is mostly an overkill for many small projects. Imagine using a super high-spec computer to play Minecraft. It's just nonsensical.
I'm assuming you'll be connecting to the car battery? Take note of the power requirements of your project. The RaspberryPi has a power requirement of 2.1A at 5V (which is a lot!), whilst an Arduino has a minimum requirement of 250mA.
Also remember: the RaspberryPi is running an operating system in the background in order to run your code. It will be working on numerous other operations and programs, not just yours. The Arduino will only run your program.
I had a similar project to what it sounds like you're doing. I used an Arduino Mega and had Bluetooth, GPS, and SD card all connected to it. The project worked absolutely fine, and I had lots of spare program space left over should I wish to expand on it. For reference, feel free to explore.

52078: <p>I am doing a project on Vehicle tracking and security. In my project Micro controller will sense input from sensors and at the same time it has to sense signal from user for tracking purpose and continuously checking the speed limit and boundary. so, there will be 3-4 tasks that would be executing parallel. Can anyone suggest which one is perfect for this kind of project... Arduino-Mega or Rasberry Pi? </p>
 7689: <p>A RaspberryPi is essentially a small, low-spec computer. It is mostly an overkill for many small projects. Imagine using a super high-spec computer to play Minecraft. It's just nonsensical.</p>

<p>I'm assuming you'll be connecting to the car battery? Take note of the power requirements of your project. The RaspberryPi has a power requirement of <a href="https://www.raspberrypi.org/products/raspberry-pi-3-model-b/" rel="nofollow noreferrer">2.1A at 5V</a> (which is a lot!), whilst an Arduino has a minimum requirement of <a href="https://playground.arduino.cc/Learning/WhatAdapter" rel="nofollow noreferrer">250mA</a>.</p>

<p>Also remember: the RaspberryPi is running an operating system in the background in order to run your code. It will be working on numerous other operations and programs, not just yours. The Arduino will only run your program.</p>

<p>I had a similar project to what it sounds like you're doing. I used an Arduino Mega and had Bluetooth, GPS, and SD card all connected to it. The project worked absolutely fine, and I had lots of spare program space left over should I wish to expand on it. For reference, <a href="https://www.instructables.com/id/DIY-Telematics-Box/" rel="nofollow noreferrer">feel free to explore</a>.</p>
