3.9 Figure 15 shows our central projection for GHG emissions from HGVS to 2050, based on current firm and funded policies. This shows that HGV GHG emissions are projected to fall by 26% from 2018 to 2050, despite a projected increase in HGV km of 7% over the same period. Emission savings are driven by the new 2030 HDV CO₂ regulations74, alongside baseline efficiency improvements driven by the market. As noted previously, the uncertainty surrounding projections is significant and other outcomes to the one shown are possible. 3.10 The regulation for HDV vehicle manufacturers making new vehicles requires reductions of 15% for 2025 and 30% for 2030 against a 2019 baseline and includes incentives for sales of zero and low emission HDVs. As committed to in the Road to Zero strategy, now that the UK has left the EU it will pursue a future approach that is at least as ambitious as the current arrangements for vehicle emissions regulation. Historic emissions are final UK GHG statistics. Historic vehicle km are from road traffic statistics. HGV emission projections are made using the National Transport Model and the Great Britain Freight Model, with inputs from the Road Carbon and Fuel Fleet Model. These models aim to forecast long-term trends over 5-year intervals with a base year of 2015 and may not capture short term fluctuations. This leads to an apparent drop in GHG emissions in 2019 when the modelled data is adopted. Modelling assumes HGV efficiency improvements. These are driven by incentives to improve efficiency driven by HGV operators and manufacturers and the 2030 CO₂ regulations.