The CO2 display shows you how much CO2 your engine is generating.
If your vehicle has an emissions certificate, it may show a 'CO2' rating as something like: 223g/km
The CO2 display in Torque may show a larger figure than this. Don't be alarmed, as this is to be expected. The test performed for the emissions certificate shows the 'best possible' figure achievable for the vehicle(it is also in the manufacturers interest to get this figure as low as possible, so keep this in mind). In contrast, real-life driving is often significantly different, and therefore you may find that your measured emissions figure isn't even close!
This display depends on the vehicle profile information being setup accurately.