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Front License Plate - Impact on MPG?

Discussion in 'Gen III 2010+ Prius Fuel Economy' started by spietrek, Oct 29, 2009.

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  1. spietrek

    spietrek New Member

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    Today I picked up my new license plates. Living in OH, it is the law that cars must have both front and rear license plates. Although I see many vehicles, especially luxury brands (Lexus, MB, Cadillac) without front license plates in the area, not sure I want to take a chance. The thought of drilling 2 holes in a perfectly good bumper <shudder> plus the fact it will definitely reduce the look of the front of the car make me quite uneasy. The law is the law so it doesn't matter what I think anyway. Just wondering what are people's thoughts on the impact on MPG? I assume there would be some hit (<1 MPG, 1MPG, more).
  2. lamontcranston

    lamontcranston Umbra Tenet

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    I wonder the same thing myself. But then again, here in California it seems the license plate holders come attached to the car when you buy them, so the damage has been done.

    I wonder if there could be some sort of deflector that fit over the license plate that could mitigate the MPG loss.
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  3. spietrek

    spietrek New Member

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  4. drees

    drees Senior Member

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    Zip tie it to the grille opening - that way you get a partial grill block year round - may be enough to improve fuel economy a smidge!

    Either way, effects on aero should be minimal since the bumper s so flat, anyway.

    Those swivelling plate mounts are designed to allow more air into the grille - not really necessary on the Prius. Keep air out of the grille should improve fuel economy.
  5. rrolff

    rrolff Prius Surgeon

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    OMG MPG:cool:
  6. Indyking

    Indyking Happy Hyundai owner...

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    Will fall leaves over my Prius impact the MPG?
  7. Blind Guy

    Blind Guy New Member

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    * I can't imagine there would be much of a hit, since the Front Bumper has a relatively high verticle stance, and thus, acts like a virtual Air Damn. The Front Plate stands above the top of the Bumper a very little, and the Plate extends below the bottom of the Bumper a little more, but I don't think they would affect MPG perceptably.

    David (aka Blind Guy)
  8. RoyThePriusGuy

    RoyThePriusGuy New Member

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    You've got to be kidding... really - can it be THAT much? 1MPG due to a .001 more drag at 55mph? c'mon...

    I have a suggestion. Keep the front plate on and take the hit. And simply drive a few less miles per week. Like walk to Starbucks. Or forego that donut and save a few pounds off the bod. That will balance out your "MPG hit"....

    Are we THIS anal about MPG? Perhaps eliminate the rear plate so we don't take the mpg hit when driving in reverse...
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  9. gohybrid

    gohybrid New Member

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    Of course, you could cut a license plate sized hole in the bumper, patch over it with .063 lexan to retain your bumper contour, and secure the license plate behind it.

    of course, if you're worried about drilling holes, you can't be too jazzed about going at it with a dremel. "Air damn" indeed. ;)
  10. xbdude

    xbdude opticat

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    Yay for RonThe PriusGuy. Finally some common sense emerges . . . . . .
  11. cossie1600

    cossie1600 Active Member

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    Let's remove the rear wipers, spoiler and sideview mirrors, less drag!
  12. rrolff

    rrolff Prius Surgeon

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    I think it has been clearly shown that tires do directly affect mileage due to drag and friction.

    You will get your most bang-for-buck by simply removing the tires.
  13. radioprius1

    radioprius1 Climate Conspirisist

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    Wind tunnel tst
  14. JimboPalmer

    JimboPalmer Nadir of Wrongness

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    I am betting driving with the dome light on will effect gas mileage more than having a front plate.

    (bwilson4web will show up with spreadsheets to prove me wrong, watch)
  15. Rokeby

    Rokeby Member

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  16. Leakman

    Leakman New Member

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    I was going to buy some triple edge wiper blades for the car but now I will have to re-think that plan. Could be a drastic change that I would have never even given a thought.

    I am heading out to polish the underneath of the car to try and reduce some of the drag!
  17. bwilson4web

    bwilson4web 03 and 10 Prius

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    Mount it on the bumper air intake, radiator block and don't worry about it it. Between the radiator block and the license plate, it will help keep the air laminar as it flows up and down under the car with a minimum of drag. Worse comes to worse, vacuum form a clear plastic cover, radiator block and mount the license plate behind the bubble. In the summer, remove the sides and you should be good to go.

    To see what I mean, look for Ken@Japan's photos of the Japanese Prius owners. The clever ones have extended their front license plate down so it always partially blocks the air inlet.

    Bob Wilson
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  18. radioprius1

    radioprius1 Climate Conspirisist

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    Is there anyone on this forum scientifically inclined enough to understand bwilson's graphs? I try and get lost immediately. Every single time :) That dude is a sharp cookie!
  19. JimboPalmer

    JimboPalmer Nadir of Wrongness

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    Yes he is. I sometimes feel I understand what he has drawn, I never feel I could be through enough to generate the data he has amassed.
    He is an asset we are lucky to have. (I may go thank a couple of posts just to show we care)
  20. a64pilot

    a64pilot Active Member

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    Funny thing is, let gas go north of $4 again, and a completly different tact will be taken on questions of whether or not there is a mileage penalty of a front license plate or not.
    In my opinion, it was a valid question, FE is gained by many small gains, not usually one big one
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