Asymmetric Substitution and Energy Import Dependence: A Non-Linear Assessment of the Transport–Energy–Tourism Nexus in a Constraints-Driven Economy

The energy implications of transport electrification are presumed to fall on the power grid, yet the fuel and electricity margins are rarely examined in parallel, and never in a tourism-driven economy heavily dependent on imported electricity. This paper takes Macau—where approximately ninety percent of electricity is imported, supply reliability is saturated, and tourism dominates demand—as an extreme case. Using monthly data from January 2010 to July 2026, we estimate within a nonlinear autoregressive distributed lag (NARDL) framework the long-run equilibrium associations between electric vehicle (EV) penetration and two distinct dimensions, namely gasoline consumption (fuel substitution margin) and electricity import dependence (electricity margin). Bootstrap bounds testing accommodates the near-I(2) character of the penetration series. The fuel margin shows a negative long-run association, with log-form point estimates spanning −0.27 to −0.62. The association is statistically firm in the full and handover windows, whereas the EV-era estimate halves to −0.27 and loses conventional significance once residual seasonality is corrected. Identification is contingent on the diffusion trend, so the range is interpreted as an upper bound on substitution rather than a magnitude attributable to electrification alone. The electricity margin shows a bounded null: eight of nine specifications yield no detectable association; the sole significant estimate is form-dependent and inconsistent with observed trends. Minimum detectable effect calculations and the observation that charging load constitutes less than 0.4% of total electricity consumption jointly bound any plausible effect. Tourism exhibits asymmetry consistent with a ratchet in the full and handover windows, where the elasticity with respect to visitor inflows (0.08–0.09) exceeds that of outflows (0.05–0.07), with the pattern attenuating under alternative specifications. In this constraints-driven tourism economy, electrification is reshaping the fuel ledger while the electricity ledger remains undisturbed.