Across five field experiments with employees of a large organization (N=68, 915), we examined whether standard behavioral science interventions (i.e., ‘nudges’) successfully reduced single occupancy vehicle commutes. In Study 1-2, we sent letters and emails that included standard nudges to increase carpooling. These interventions failed to meaningfully increase carpool sign-up or usage. In Studies 3-5, we examined the efficacy of two other well-established behaviorally-informed interventions: non-cash incentives and personalized travel plans. Again, we found no meaningful effects. Across studies the effect sizes were d=[-0.01, 0.05], with a meta-analytic effect size of d = 0.02, 95CI [-0.02, 0.06]. Equivalence testing reveals that the effect size of four of the studies is statistically equivalent to zero (p < 0.0001). Our paper presents the first set of highly powered behaviorally informed experiments on these outcomes and highlights the importance of publishing null results to build cumulative knowledge about how to encourage sustainable travel.