As the gaming industry has grown, many games allow players to customize their character. Research shows that character customization enhances avatar identification, and avatar identification affects many aspects of a player, including psychology, behavior, arousal, learning, and self-building. Few studies focus on the interaction between avatar identification and performance in racing games. The character types in racing games are different from those in other games. In kart racing games, players can see their character and the kart at the same time. When players can customize two different types of avatar and see them simultaneously in the game, I wonder how avatar customization affects avatar identification and performance. A kart racing game was designed and developed to study the influence of the combination of different types of avatar on avatar identification and player performance. I compared four groups of participants. In the first three groups, players customized different avatar types: (1) driver and car, (2) driver only, (3) car only, and the control group with (4) the default character and kart. The research collects avatar identification and player experience through a questionnaire, and collects player performance through in-game data. I expect to find that the group customizing the combination of character and kart leads to higher avatar identification, better performance and experience. This study demonstrates the importance of combination of avatar types in video games.