I drive a 2004 Toyota Camry.  It has an incredibly stupid speedometer.  I drew a picture to illustrate my point. 
[Image: speedometer.png]
Each interval of 10 mph is divided into 4 parts.  The problem with that is that 10 divided by 4 doesn't equal a whole number.  It equals 2.5, which means I can only be sure of my speed in multiples of 2.5, e.g. 40, 42.5, 45, 47.5, 50, etc.  Most speedometers are divided into whole number intervals such as 1 or 2, which makes sense since cops don't care if you were going "around 67.5". 

I really can't figure out why Toyota's speedometer designer decided to do this.  One argument may be that it's a Japanese car, so maybe it has something to do with the Japanese numbering system and/or converting between kph and mph.  Wrong.  The kph scale is divided into the same intervals, and both Japan and the U.S. use a base-10 numbering system, which means that 10 divided by 4 will always equal 2.5 (as opposed to something like base-8, where intervals of 2.5 would be intervals of 2). 

Another argument could be that Toyota has no experience designing cars and/or speedometers.  That's obviously not true since Toyota's been around for about 50 years and makes several of the best-selling cars on the planet.  They've obviously designed a few speedometers in their day. 

The only argument for designing it this way is that pretty much all speed limits are multiples of 5 (except in places like Virginia, which has speed limits like 8 and 16 in places), so at least you'd always know the exact point on your speedometer that refers to the speed limit.  But if that's the case, why put two more dividers at 2.5 and 7.5?  That just doesn't make sense. 

The thing that gets me is that this speedometer was actually designed.  Somebody was in charge of this.  A decision was made to make it this way.  This wasn't a mistake.  "It's not a bug, it's a feature."  I'd like to have a word with this person. #travel