SHANGHAI (Reuters) - Shares in Chinese automakers Xpeng and Geely Auto tumbled on Tuesday on worries that they will struggle to compete against BYD's move to offer smart driving features across almost all of its line-up for free.

Xpeng's shares fell 5.9%, their biggest decline in two months, while Geely fell 7.2%. BYD's Hong Kong-listed shares added 0.9% to reach a record high.