An AIM Solo DL can be tied directly into the CAN bus of the car. (They also have an OBD option that I've never tried.) The CAN bus streams quite a bit of live data. A single page on the AIM can be configured to display up to 4 live parameters of your choosing. The AIM can easily be suction cupped (RAM mount) to the windshield. I keep it off to the left side and as low as possible. Here's what it looks like these days.
I'm considering moving it over to the dash in the middle and getting it off the windshield. Sometimes I find that even where it is in that picture, that it obstructs my view into turns. (I sit fairly low in the race seat, so I look through the lower portion of the windshield.)
The bummer part about CAN bus data is that the raw data is usually disguised. BMW doesn't publish a list of CAN IDs along with the data clearly marked. No.....it's buried as some arbitrary ID number in some unknown unit with some unknown data offset. Companies like AIM rely on outside help to provide them with info that can identify particular parameters amongst the mess of data so they can translate it into a gauge that can be shown on a screen.
DCT temps are a good example. The M3 definitely tracks DCT temps. The Awron gauge is able to track DCT temps. (Sadly, the Awron cannot log data....only shows it in realtime....) But no one else has figured out what CAN ID it is and what the Identifiers and Offsets are. So, the AIM Solo currently can't track DCT temps from the CAN bus. (I put in an analog Stack gauge to see DCT temps live. You can see the round blue gauge in the video.) I talked to AIM and they said that if someone could tell them the ID, units and offsets for the DCT temps parameter, they could easily add it to their list of available parameters. (The Solo DL can log up to 64 parameters, but is currently tracking less than that.) There are people who have figured out a bunch of different CAN IDs, but unfortunately I have not seen anyone publicly disclose the DCT CAN ID.
Anyway, the AIM Solo DL can not only show you realtime info while in the car, but it can also record it all so you can analyze it later on a pc. I have made many improvements to my driving by looking at data recorded by the Solo DL.