Ah, I see now... Trip values are in the trip summary mode, not in a gauge. After reading the manual I see the XGauge mode allows you to add it as one of the four realtime gauges like RPMs and MPH. I have just been swapping between realtime (gauge) and summary (trip/tank) modes while driving... maybe using the XGauge mode is safer.
I'll try that this week, probably.
Has anyone tried the Instant Horsepower XGauge commands?