diff --git a/macrovision.js b/macrovision.js
index 1c7f98d9..9d111d9c 100644
--- a/macrovision.js
+++ b/macrovision.js
@@ -158,6 +158,14 @@ math.createUnit("peopleMass", {
     definition: "80 kg",
     prefixes: "long"
 });
+math.createUnit("cars", {
+    definition: "1250kg",
+    prefixes: "long"
+});
+math.createUnit("buses", {
+    definition: "15000kg",
+    prefixes: "long"
+});
 math.createUnit("earthMass", {
     definition: "5.97e24 kg",
     prefixes: "long"
@@ -264,6 +272,8 @@ const unitChoices = {
         ],
         "relative": [
             "peopleMass",
+            "cars",
+            "buses",
             "earthMass",
             "solarmasses"
         ]