Not really a mod, but a very simple thing to do and this do change the reaction of people on the road :
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It says "consumption 67mpg - 1056mi/tank - and you ?".
Before that the reactions were mainly by young males driving tuned cars and thinking that the only reason to have a car is to go fast. Which is more than funny when their rear doors have sunshades with childish cartoon characters
Now I have several
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everyday
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noticeably from ladies and old people
But with or without this paper, the best overall is the smiles ans astonished eyes from children seeing the car
Have fun,
Denis.
__________________
Save money & CO2 at home :
http://ecorenovator.org/ 
Created and managed by the creators of
http://ecomodder.com/ 
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Earth and health are priceless, so are kilotank and AT-PZEV
Best Mégane tank: 1268.9mi @ 77.847 MPG(US)
2008/06-2011/10 saving:
- 5725.5 kg CO2 (5342.6+382.9)
- Diesel / Money: 42.17% = 2446.25€ = 3357.26$
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megane :
thread -
kill switch.