In a new report, Navigant Research estimates that nearly 84.1 million new light-duty vehicles (LDVs) will be sold globally in 2014, putting more than 1.2 billion vehicles on the world’s roads.

The company forecasts that annual LDV sales will grow to 126.9 million in 2035, representing a compound annual growth rate (CAGR) of 2.0%. The number of LDVs in use worldwide will grow by 72.4% over the forecast period—i.e., to more than 2 billion vehicles.Navigant forecasts that sales of conventional ICE vehicles will fall significantly over the period, experiencing a CAGR of -6.7%; the share of vehicles in use with conventional ICE powertrains will thus fall from 95% in 2014 to 45% in 2035. Navigant suggests that conventional ICE vehicles will be mainly supplanted by stop-start vehicles (SSVs), which will grow from representing fewer than 3% of vehicles in use in 2014 to around 45% in 2035.

Hybrid-electric and natural-gas (HEVs and NGVs) will account for almost 8% of global share, while plug-in hybrid (PHEV), battery-electric (BEV), and fuel-cell electric (FCV) together will add up to almost 2.5% of the LDVs in use in 2035.

Although most governments have supported a comprehensive strategy to reduce oil dependency in the transportation sector, the depth of that support varies with each vehicle technology, Navigant notes.

Additionally, regional fuel costs and refueling infrastructure availability play a major role in consumer acceptance of alternative fuels regardless of government backing. Therefore, the firm concludes, the adoption of light duty (LD) alternative fuel vehicles (AFVs) and fuel efficient technologies will vary significantly from region to region.

While the landscape for vehicle technologies will change significantly, alterations to the primary fuel landscape will be more modest. LDVs primarily fueled by gasoline will fall as a percentage of the overall global fleet from 82% in 2014 to 75% in 2035. Fuel efficiency gains from diesel engines will increase diesel’s share of the fleet from 16% in 2014 to 19% in 2035. By 2035, more than 4% of vehicles will be fueled by natural gas and less than 1% by hydrogen. Vehicles fueled exclusively by electricity will represent 1% of global LDVs in use; however, PEVs (which also includes PHEVs) will represent almost 1.7%.