I bought this clock and want to stick it onto the dasboard but the 3M stickers that came with it just slide right off.

 

Taste is personal, and here's mine: There is no tape that would stick that to my dash. An office desk, perhaps. The dashboard of a Benz? NFW.
But: Clean your dash well with denatured alcohol in the spot you plan to violate. Use 3M automotive trim adhesive double sided gray foam tape (conveniently available in a couple of different widths) and have at it.

 

i use this on my boat.

ron

 

The ML is a second car for me, and no matter how many places it displays the time of day digitally, I'm always glancing at the middle of the dash where my SL (and all of my past cars, IIRC) has an analog clock:

 

I had it on the dash but it looked out of place, like it might roll off. I moved it to a spot where it can really only be seen from the driver's seat. Much better.