user49399: Help me to choose a power source for the below project:

4x DC Motors (3V~6V DC each with ~170mA),
1x Micro Servo Motor (4.8V~6V),
1x Ultrasonic sensor
1x Bluetooth sensor

It is basically an RC car. The project runs on Arduino UNO and it uses Motor Shield (1.2) to power up those five motors. The motor shield does support external power supply. Shall I go for that, or Arduino can power up the entire system altogether?

user4143: 2S LiPo with 5V UBEC is what you want.  Hit your favourite RC model seller for those.  I use HobbyKing (as the links show).
The capacity choice of the LiPo depends on

How much power your motors etc need, and
How long you want it to run for

You could also go for 3S or 4S to get more power if your chosen UBEC supports the voltage.

user48150: Many [fake] Arduino UNO boards on the market have an AMS1117 regulator for external power supply from 7.5v to 12v. note that it's a linear regulator and it "wastes" the excess power as heat and compared to the very demanding components you have (about 1 amps) it's obviously not an option. so no. you can't use "External" supply of Arduino to power them all. 
it's best to use separate supplies for each board. or you may Use a 5V Battery Kit and connect it to 5V pin on either shields.

49399: <p>Help me to choose a power source for the below project:</p>

<ul>
<li>4x DC Motors (3V~6V DC each with ~170mA),</li>
<li>1x Micro Servo Motor (4.8V~6V),</li>
<li>1x Ultrasonic sensor</li>
<li>1x Bluetooth sensor</li>
</ul>

<p>It is basically an RC car. The project runs on Arduino UNO and it uses Motor Shield (1.2) to power up those five motors. The motor shield does support external power supply. Shall I go for that, or Arduino can power up the entire system altogether?</p>
 4143: <p><a href="https://hobbyking.com/en_us/batteries-chargers/batteries/lipo.html?config=52" rel="nofollow noreferrer">2S LiPo</a> with <a href="https://hobbyking.com/en_us/power-systems/power-distribution/vr-ube-bec-sbec.html" rel="nofollow noreferrer">5V UBEC</a> is what you want.  Hit your favourite RC model seller for those.  I use HobbyKing (as the links show).</p>

<p>The capacity choice of the LiPo depends on</p>

<ul>
<li>How much power your motors etc need, and</li>
<li>How long you want it to run for</li>
</ul>

<p>You could also go for 3S or 4S to get more power if your chosen UBEC supports the voltage.</p>
 48150: <p>Many [fake] Arduino UNO boards on the market have an AMS1117 regulator for external power supply from 7.5v to 12v. note that it's a linear regulator and it "wastes" the excess power as heat and compared to the very demanding components you have (about 1 amps) it's obviously not an option. so no. you can't use "External" supply of Arduino to power them all. </p>

<p>it's best to use separate supplies for each board. or you may Use a 5V Battery Kit and connect it to 5V pin on either shields.</p>
