Transportation contributes to a significant and rising share of global energy use and GHG emissions. Therefore, modeling future travel demand, its fuel use, and resulting CO2 emissions is highly relevant for climate change mitigation. In this study we compare the baseline projections for global service demand (passenger-kilometers, ton-kilometers), fuel use, and CO2 emissions of five different global transport models using harmonized input assumptions on income and population. For four models we also evaluate the impact of a carbon tax. All models project a steep increase in service demand over the century. Because technology change is important for limiting energy consumption and CO2 emissions, the study also shows radical changes would be required in order to stabilise or even decrease emissions. While all models project liquid fossil fuels dominating up to 2050, they differ regarding the use of alternative fuels (natural gas, hydrogen, biofuels, and electricity), because of different fuel price projections. The carbon of 200 USD/tCO2 in 2050 stabilizes or reverses global emission growth in all models. Besides common findings, many differences in the model assumptions and projections indicate room for further understanding long-term trends and uncertainty in future transport systems.