When it comes to "personalizing" a badge or card, templating is the easiest go-to option. I made this example as a proof-of-concept just to see if I could do it and I still use it today. (It is probably more complicated than it needs to be as I'm sure the badge probably does most of this by default nowadays.) This is for my phone but should be easily adapted to your car.
type: custom:mushroom-chips-card
alignment: center
chips:
- type: template
entity: sensor.s25_ultra_battery_level
content: |
{% if states(entity) != 'unknown' %}
{{ states(entity) }} {{ state_attr(entity, "unit_of_measurement") }}
{% else %}
???
{% endif %}
icon_color: |
{% set battery_level = (states(entity) | int) %}
{% if battery_level >= 90 %} green
{% elif battery_level >= 80 %} light-green
{% elif battery_level >= 68 %} orange
{% elif battery_level >= 56 %} yellow
{% elif battery_level >= 44 %} amber
{% elif battery_level >= 32 %} orange
{% elif battery_level >= 20 %} deep-orange
{% else %} red
{% endif %}
icon: |
{% set battery_level = states('sensor.s25_ultra_battery_level') | int // 10 * 10 %}
{% set charging_state = states('sensor.s25_ultra_charger_type') %}
{% set is_charging = is_state('binary_sensor.s25_ultra_is_charging', 'on') | iif(True, False) %}
{% set map = {"none":"", "ac":"charging-", "wireless":"charging-wireless-"} %}
{% set charging = map[states('sensor.s25_ultra_charger_type')] %}
{% if battery_level == 100 and is_charging == True %} mdi:battery-charging
{% elif battery_level == 100 %} mdi:battery
{% elif battery_level >= 10 %} mdi:battery-{{charging}}{{battery_level}}
{% elif battery_level >= 0 %}mdi:battery-{{charging}}outline
{% else %} mdi:battery-unknown
{% endif %}
tap_action: none
hold_action: none
double_tap_action: none