Just to give an update I bought this from aliexpress:
Auto Trip Computer Car Multi function Information Display Diagnostic Tool with OBDII Clear Car Fault Code Show All Informations-in Code Readers & Scan Tools from Automobiles & Motorcycles on Aliexpress.com | Alibaba Group
It works really well, you can adjust the speed calibration factor so the speed and distance are in mph, although the displays still says kph. The mount it came with was rubbish and broke the first time I tried to use it. I've used an old phone mount which works well. It can display a ton of information, lambda voltage, current operation mode open/closed, intake temperature, coolant temperature, ignition advance, fuel trim and a load more.