The bumpers on a car decrease MPG

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Discussion Overview

The discussion centers around the impact of car bumpers and shock absorbers on vehicle performance, specifically regarding energy loss and fuel efficiency (MPG). Participants explore the relationship between suspension dynamics and energy absorption, considering both theoretical and practical implications.

Discussion Character

  • Exploratory
  • Technical explanation
  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • One participant, Vidar, proposes that bumpers create friction in the suspension system, leading to energy loss and questioning the extent of this loss in relation to car weight and suspension travel.
  • Another participant references a study on energy-harvesting shock absorbers, suggesting that they can potentially increase fuel efficiency by 1-4% for conventional cars and up to 8% for hybrid vehicles.
  • Some participants argue that shock absorbers may absorb energy that would otherwise be lost, potentially reducing overall energy losses by stabilizing the vehicle's motion.
  • There is a mention of the possibility of extracting energy from shock absorbers, which could further enhance fuel efficiency.

Areas of Agreement / Disagreement

Participants express differing views on the role of bumpers and shock absorbers in energy loss and fuel efficiency. While some acknowledge potential benefits from energy harvesting, others question the net effect of friction and energy absorption, indicating that the discussion remains unresolved.

Contextual Notes

Participants do not fully agree on the definitions of energy loss and efficiency in the context of bumpers and shock absorbers, and the discussion includes assumptions about vehicle dynamics that are not fully explored.

Who May Find This Useful

This discussion may be of interest to automotive engineers, researchers in vehicle dynamics, and individuals exploring energy efficiency in transportation technologies.

Low-Q
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Hi,

I have thought about how the bumpers affects the performance of the available power in a car engine. The bumper applies friction to the suspension so the car doesn't jump off a bumpy road. However, that friction will be a sort of energy loss. The questions is: How much energy loss is it at a given car weight and suspension travel pr. time? By how much will that decrease MPG?

Vidar
 
Physics news on Phys.org
Oh you mean the shock absorbers...

http://blogs.discovery.com/files/energy-harvesting-shock-absorber-june-2011.pdf

Energy Harvesting Shock Absorbers

snip

We estimated that for a middle-size vehicle, 100W, 400W, and 1600W of average power is available for harvesting from the regenerative shock absorbers while driving on Class B (good), C (average), and D (poor) highways at 60 mph.

snip

This represents a potential of 1-4% fuel efficiency increase in conventional cars and up to 8% for hybrid vehicle.
 
I think they absorb energy which would be lost anyway - just in other parts of the car. They can even reduce losses, if they keep the whole car from bumping around.
If that energy can be extracted: Even better.
 
CWatters said:
Oh you mean the shock absorbers...

http://blogs.discovery.com/files/energy-harvesting-shock-absorber-june-2011.pdf
Yes that's correct :-) I used google translate from Norwegian...
Well, thanks for the link :-)

Vidar
 

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