SelfCritic-VLA: Language as Intrinsic Critic for Vision Language Action Models in Autonomous Driving

Vision-Language-Action (VLA) models offer a promising paradigm for end-to-end autonomous driving by connecting visual scene understanding, linguistic reasoning, and low-level trajectory generation. However, existing driving VLAs typically use language only as static commands or supervised rationales, while treating trajectory prediction as an open-loop generation problem. As a result, they lack an explicit mechanism for understanding the consequences of their own actions, which limits robustness under closed-loop distribution shift and makes reinforcement learning inefficient in long-tail scenarios. We propose SelfCritic-VLA, a self-evaluative VLA framework that unifies trajectory generation, language-grounded action critique, and trajectory refinement. Given a driving scene, the model first generates an initial trajectory, then produces a language-grounded critique that describes the potential safety, progress, and rule-compliance consequences of executing that trajectory, and finally refines the trajectory conditioned on this critique. To train this capability, we construct a large-scale counterfactual trajectory dataset with multi-source candidate trajectories and semantic critiques, and perform hybrid supervised fine-tuning for planning, action evaluation, and refinement. Building on this initialization, we introduce a self-critic reinforcement learning procedure based on GRPO, where critique-conditioned refinements are filtered by grounded driving rewards and distilled back into the base policy. Experiments on NAVSIM and Bench2Drive show that SelfCritic-VLA consistently improves both open-loop and closed-loop driving performance over strong baselines, demonstrating the effectiveness of language-guided self-refinement for driving policy optimization.