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What is the wattage output of an average automobile.?

I know watts are a measure of work being done. How much wattage is required to move a 3000 lb automobile from a stop to 60 miles per hour. I'd like to know how to calculate this myself, so please show the formula you'd use to come up with the answer. I'm curious to know how significant a 250W solar collector on the roof of my hybrid car would be.

Public Comments

1. A 250W solar collector is about one third of a horsepower. How significant that is would depend directly on the friction and windage losses while driving. Also, a 250 W rated panel spends most of it life generating 125W or less. And you need to specify time or distance. Your hybrid uses the gasoline engine to accelerate and uses the batterys to run at constant mid-speed. So during acceleration the extra electrical energy would go unused. At constant speed the electrical system kicks in. If I were to guess I would say that the car uses about 12-15 horsepower to maintain 40 mph, straight and level. So the addition of an additional third of a Hp is not especially significant while you are driving the car, even at constant speed, much less while accelerating from 0 to 60. However, allowing that extra third of a horsepower to charge the batteries for 12 hours a day while it is sitting in the sun can indeed provide quite a bit of accumulated energy. But to make do that you would have to include a system in the charging system to reduce the engine charging and allow solar charging, otherwise you run the risk of overcharging and destroying the batterys. A solar charger like you mention would work better on a car with a plug-in charger, a totally electric vehicle. Unless you have this feature on your hybrid, using a solar collector to recharge it is an iffy thing that could cause system damage. Instead, maybe you can use your solar collector to power a cooling fan to cool the interior while the car sits in the sun, so you won't need as much a/c, or heat the engine oil so it comes up to operating temperature faster, making the enine more efficient, or to warm the interior on those cold but sunny days; all are ways to reduce fuel energy usage and can profit from that extra 1/3 of a horsepower. Perhaps you can think of same others.
2. use Kinetic Energy KE = ½mV² 3000 lb = 1361 kg 60 mph = 26.8 m/s KE = ½mV² plug in the numbers to get the Kinetic energy. KE = 489534 Joules to get the power (wattage), you need a time. If it accelerates to 60 in 10 seconds power = KE/10 in watts. = 489534/10 = 48953 watts. If average car uses 100 HP, that is 74600 watts. .