JSON conditional formatting for mileages

StuartReeves have a go with the following JSON:

{
  "$schema": "https://developer.microsoft.com/json-schemas/sp/v2/column-formatting.schema.json",
  "elmType": "div",
  "attributes": {
    "class": "=if(@currentField >= 3000, 'sp-field-severity--good', if(@currentField < 3000 && @currentField >= 1000, 'sp-field-severity--low',if(@currentField < 1000 && @currentField >= 100, 'sp-field-severity--warning','sp-field-severity--blocked')))"
  },
  "children": [
    {
      "elmType": "span",
      "style": {
        "display": "inline-block",
        "padding": "0 4px"
      },
      "attributes": {
        "iconName": "=if(@currentField >= 3000, 'CheckMark', if(@currentField < 3000 && @currentField >= 1000, 'Forward',if(@currentField < 1000 && @currentField >= 100, 'Error','ErrorBadge')))"
      }
    },
    {
      "elmType": "span",
      "txtContent": "@currentField"
    }
  ]
}

which results in:

Rob
Los Gallardos
Intranet, SharePoint and Power Platform Manager (and classic 1967 Morris Traveller driver)