# Power consumption of a car

by Ziv7
Tags: car, power
 P: 15 I need rough values for power consumption of an average sized car at different speeds. Does anyone know how to either calculate or where I could find such information? Thanks
 Mentor P: 21,674 How many different speeds? You can start by calculating it from the fuel economy. You can also buy devices to report fuel consumption in realtime.
 P: 15 I dont need anything exact and I don't have a specific car. I'm just interested in approximates power/fuel consumption at speeds like 30,50 & 70 mph. I'm doing a study on energy harvesting in suspension system and want to find out the % savings such systems could have on the average user.
PF Patron
P: 244

## Power consumption of a car

 Quote by Ziv7 I dont need anything exact and I don't have a specific car. I'm just interested in approximates power/fuel consumption at speeds like 30,50 & 70 mph. I'm doing a study on energy harvesting in suspension system and want to find out the % savings such systems could have on the average user.
You need weigth of the car and suspension travel during a ride. Energy output depends basicly on how bumpy the road is, the suspension compliance, weight of the car, how long distance traveled. Harvesting all the energy loss makes very stiff suspensions...
 P: 15 I know about the power harvested as I have performed an experiment and done some analysis on matlab. What I want is rough power consumption of an average car. (obviously the consumption is different at different speeds) It is just for comparison purposes to represent the % of potential energy savings such systems can lead to. Thanks
 Mentor P: 21,674 Well, for my last car, a Mazda 6, it got about 35mpg from 30-50mph and about 30mpg at 70mph. Do you know to use those values?
PF Patron
P: 244
 Quote by Ziv7 I know about the power harvested as I have performed an experiment and done some analysis on matlab. What I want is rough power consumption of an average car. (obviously the consumption is different at different speeds) It is just for comparison purposes to represent the % of potential energy savings such systems can lead to. Thanks
You would probably not save much if you want to maintain the suspension and stability properties of your car. The most energy you can extract from the suspension is having no suspension at all. Ofcourse the ride would be rather unpleasent, but mpg would increase.
Well, suspenson is not the enemy, but the suspensions damping mechanism. You can replace these dampers with coils and magnets, charging a battery and feed the electricity directly to an electric motor.
How it affects mpg depends on how the wheels bounce up and down. The average HP to maintain 50mph is approx 15 HP for a typical family car - say Mazda 6, and 35mpg. You have found the energy you can harvest from the suspension from the weight of the car and road conditions.

Then your calculations can be subtracted from the energy required to maintain velocity of 50mph on a straight and level road. That would provide the answer you're looking for.

Vidar

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