I'm guessing here, but possibly it calculates average speed over a known distance -- eg 100km is four laps of the full Nurburgring -- using the start/stop buttons.

Here's my 8T23 -- the first and as far as I am aware only manually wound quartz watch. James Dowling and @tyrantlizardrex are to blame for the show and tell at time4apint that got me into it, and the superb Kay @krogerfoot for helping get it from Japan (it is also his pic). I'm now trying to find a replacement capacitor....

 

That's an interesting theory on the giugiaro. I'll have to keep poking around until I can figure it out.

Thanks for sharing the manual wind quartz! I was able to find a nice write-up on it: https://www.plus9time.com/blog/2017/12/28/worlds-first-hand-wound-quartz-seiko-8t23.

It's funny to me - we're so used to ultra cheap quartz movements, it's surprising to think about how complex and exciting the development of these technologies were at the time - like having to figure out how to get consistent movement from the stepper motor despite changes in voltage depending on the amount of charge in the capacitor.

 

Ya I know what you were going for the strange seiko but I’m a rebel without a clue and that Credor was being sold on Reddit for 40k or so I think

 

The reissued watches (SBJG001,SBJG003 A825-00A0,A825-00B0) released in 2018 have the same features, so why not consult the manual!
You can download the PDF here
https://www.seikowatches.com/jp-ja/-/media/Files/Common/Seiko/instructions/English/A/A825/A825.pdf

 

Oh cool! Thanks! So @timjohn was correct - it's a tachy function with driving distance presets! Which, I guess makes sense with giugiaro being a car designer, among other pursuits.

 

Sorry, I didn't mean to gate-keep this thread. Credor movements are very pretty indeed.