All cars used to run on a NEDC cycle to get the quoted emissions and MPG figures. Basically it's just a standardised course that the cars must drive on (stipulated acceleration, braking, incline, temperature, speed, etc.) to see how much they emit and how much fuel they use.
Whilst this was effective at standardising the test to allow comparisons across different cars/manufacturers, it was so ridiculously unrealistic to how anyone would drive in the real world, that the figures were grossly underestimating how much the cars were actually emitting on our roads, and what kind of figures customers could reasonably expect in terms of fuel economy.
As such, they have now brought in the WLTP to take place of the NEDC cycle. An altogether more realistic text cycle that represents how normal people drive on the roads.
Since all cars will now use the figures quoted from the WLTP, and the WLTP is more rigorous than the NEDC, it's likely that the current quoted emissions will increase and MPG will decrease. If the CO2 in particular increases, then this will affect the tax bracket for new cars in terms of the VED they pay at registration. Audi can't know whether their cars will have a change in VED yet, so it's just a wait and see exercise....
I imagine it will also have a big impact on (ironically) a lot of no VAG diesels in terms of new legislation relating to NOx. Independent reports have shown a lot of diesels from other manufacturers, like Renault, emit many many times more NOx than they do during the NEDC. It's likely that they will therefore see increases doing the WLTP. VAG seemingly learned their lesson from 'DieselGate', and real world testing shows that latest EU6 VAG diesel actually emit very close to what the NEDC cycle says, so WLTP will probably show similar NOx results. Other manufacturers may struggle to get newer diesels to pass EU thresholds under the new WLTP (guess they could always borrow VAG's cheat software...), but then again most have probably already abandoned R&D spending on diesels, and focusing on EV/Hybrid....
