The temperature is the first 'page' of the OBC.
If you turn on the OBC you get the temperature, if you add a button (search OBC hack) you can cycle through the 'pages' from temperature, to miles to empty, average MPG, average speed, and the most useless feature ever, speed gonging.
Just in case your where wondering, the Boxster does have a negative sign. Took this last year, I think it got down to -17° once, but I didn't have a camera handy.
