Why a Scooter and the Prius Get the Same MPG
Posted by Max Dunn Sat, 25 Jul 2009 14:57:00 GMT
A friend of mine recently got a 400cc Suzuki Burgman scooter and loves it. He gets 53 MPG which is pretty good, but realized that it was about the same as a Prius that gets 48 MPG. “Why is this?”, he asked. The Prius weighs about 3000 lbs while the scooter is only 400 lbs.
Let’s look into this.
Regenerative Breaking
Even though the scooter is a lot lighter, the Prius captures about 50% of the energy when breaking and uses it to accelerate. So this brings the effective weight of the Prius down to 1500 lbs.
Wind Resistance
Even though the scooter has a frontal area 4 times smaller than a Prius, a scooter is not very smooth going through the air. It has a coefficient of drag (Cd) of about 0.9 versus about 0.26 for the Prius. Adding this up, the total drag coefficient (Cd x A) for the Prius is 6.24 and the scooter is 5.4. This means that the scooter takes almost as much energy to overcome wind resistance as the Prius!
Motor Efficiency
Small engines are not very efficient, while Prius engines are very efficient.
Conclusion
Add them up: the extra weight is not as significant because of regenerative breaking, the wind resistance is about the same and the motor is much less efficient. Given all this, it is not surprising that the scooter and the Prius get about the same gas mileage!