  The provision of natural language explanations for the predictions of
deep-learning-based vehicle controllers is critical as it enhances transparency
and easy audit. In this work, a state-of-the-art (SOTA) prediction and
explanation model is thoroughly evaluated and validated (as a benchmark) on the
new Sense--Assess--eXplain (SAX). Additionally, we developed a new explainer
model that improved over the baseline architecture in two ways: (i) an
integration of part of speech prediction and (ii) an introduction of special
token penalties. On the BLEU metric, our explanation generation technique
outperformed SOTA by a factor of 7.7 when applied on the BDD-X dataset. The
description generation technique is also improved by a factor of 1.3. Hence,
our work contributes to the realisation of future explainable autonomous
vehicles.
