coolcow

I drive by a radar speed "feedback" sign ("your speed is..." sign) every morning. It is downhill. I've noticed what the sign shows is consistently (1~3mph) less than what my speedometer says. But on my Accord, the numbers are quite close.

I wonder if my car needs calibration or it is just the shape of ES350 that fools the rador detector?

GumboChief

Try to borrow a handheld gps unit from a friend.

While there is a 1-2 second lag, most units are good for plus or minus 1 mph.

onsknht

Are you driving by at the posted limit?

Naughty you if you aren't!

Ha!

FWIW - - I have an uncontrollable urge to see if I can get the largest number on them things!

MD350

I went down a road that had 1 speed display on each side. Going south, mine was off a few mph. Going back north a few hours later, I was right on the money. I don't think they are very accurate.

Lexmex

Good point. I rattled off 120.9 mph with a 112 mph fuel cutoff in my RX, but the GPS does not lie as much.

Irishfan

Every single car on the market has an "optimistic" speedo. How optimistic depends on the manufacturer. Rumor has it BMW is one of the guiltiest parties out there.

Keep in mind it's usually not a solid number of mph over, but usually at a ratio. This is purposely added by the manufacturer, and apparently is a "safety" feature to keep people from going as fast.