Included with my receipt for my 2019 Macan 2.0T was the Certificate of Conformance that applies specifically to my car, it's a 4 page document written in German. This shows the Correlated NEDC emission and consumption figures for Urban, Extra Urban and Combined (these are the same values that are shown on the Porsche web site) but it also shows the data that has been measured by the WLTP emissions test which is much more comprehensive. VED rates will continue to be based on the Correlated NEDC values but the government has proposed that they will change from April 2020 to use the full WLTP data for CO2 emissions. At the moment the 2.0T with 185g/km has a first year rate of £830 (rises to £855 April 2019) and for the 3.0S it is £1240 (rises to £1280 from April 2019).
From 6th April 2020, if the government gets it's proposal through then there could be a significant increase in first year VED rates for all cars (not just Porsche) following the changeover to using WLTP to determine the first year VED rates. The industry predicts a 10% to 20% increase in the CO2 emissions data that will be used for BIK, VED, and employers NI contributions as a result of the switch. However as you can read on the web site links below there is a move to ensure that this "increase" in emissions should not impact financially on consumers. However, if the government sees an opportunity to extract more tax by moving cars up into higher emissions bands will they resist the temptation?
As the WLTP web site mentions, in reality the emissions and consumption of the cars has not changed, it's just the new measurement procedure gives a more realistic result of what the actual values are compared to what NEDC measured.
For my Macan 2.0T the CoC shows both the NEDC and the WLTP measurements
NEDC
Urban - 218 g/km - 9.5 l/100km - 29.7 mpg
Extra Urban - 166 g/km - 7.3 l/100km - 38.7 mpg
Combined - 185 g/km - 8.1 l/100km - 34.9 mpg - This is the figure used to determine the first year VED rate of £830
WLTP is measured at 5 values
Low - 295 g/km - 13.0 l/100 km - 21.7 mpg
Middle - 222 g/km - 9.8 l/100 km - 28.8 mpg
High - 198 g/km - 8.7 l/100km - 32.5 mpg
Extra High - 249 g/km - 11 l/100km - 25.7 mpg
Combined - 233 g/km - 10.3 l/100km - 27.4 mpg - This is the figure that would be used to calculate VED from 6th April 2020
I have driven my car just over 400 miles since delivery, it's obviously not run in and it is on winter tyres but so far it's showing an overall average of 28.2 mpg on the trip meter which is consistent with the WLTP combined figure.
If you want to know more have a look here
http://wltpfacts.eu/from-nedc-to-wltp-change/ and here
https://www.vehicle-certification-agenc ... b/wltp.asp
From January 2019 the WLTP figures will be available through a link on the VCA web sites so it will be interesting to see how the 3.0S compares, my guess is that it will be worse than the 2.0T in proportion to the NEDC figures for the combined figure.