+1 on the positive comments. Hugely effective and I use almost all the time in Virginia, where there are few road speed sensors and many, many police crossovers and traps. Saved me 4 times over the July 4th weekend alone.

In NC I often leave it off because everyone seems to be speeding anyways and the state troopers simply just aren't around or don't give a crap about going 5 over the limit. The K-band speed sensors throw false alerts frequently and give me a heart attack everytime I pass one.

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2014 Mazda 3 GT: Ø Consumption: (click for details)