Anthony Wiskich2026-11-022026-11-022206-0332https://hdl.handle.net/1885/733816709Autonomous and electric vehicles could shift personal travel from aviation to roads, changing a basket of external costs – climate, accidents, noise, air pollution and land. We estimate the effect for European personal travel with a parsimonious discrete-choice model of car, rail and air, whose substitution elasticity sets a nonlinear “modal cliff” – the car-to-air switch as distance rises – estimated on European modal splits. Re-parameterising the car for a mature autonomous electric fleet draws travellers from both aviation and rail: personal air passengers on land-connected routes fall by a quarter (24.6% centrally, 18% to 32% across plausible distaste for driving, the key uncertainty). Because emissions concentrate in longer flights cars cannot replace, the shift reaches about a fifth (19%) of land-connected aviation CO2e and cuts its external cost by as much: with an electric fleet a switched flight’s warming is avoided almost in full, and short-haul switchers shed disproportionate noise and air-pollution costs. Automation neutralises driving’s accident cost and electrification its climate cost, more than halving driving’s external cost from 5.1ct/pkm to 2.2ct/pkm at a conservative 100€ per tonne CO2.enaviation, autonomous vehicles, rail, modal substitution, external costs, discrete choice2026-10-27