Drive at a blue car at thirty and you pass straight through it. Crawl into the same car at two and you pass through it just the same. Contact is not damage, and what separates a nudge from a wreck is a number nothing in this scene has measured yet: how fast the gap between two cars is closing.

A second pool, in red

The traffic pool already taught the shape — a blueprint entity carrying a Pool marker beside the components its offspring get, consumed at load once its slots are stamped out. EnemyBlueprint is that shape again, in red, with one addition:

"EnemyBlueprint": {
  "tags": ["enemy"],
  "components": {
    "Pool": { "name": "enemy", "size": 8 },
    "MeshPrimitive": {
      "primitive": "box",
      "width": 1.9,
      "height": 1.1,
      "depth": 4.4,
      "material": {
        "diffuseColor": [0.7, 0.14, 0.16],
        "emissiveColor": [0.2, 0.03, 0.03],
        "specularColor": [0.2, 0.2, 0.2]
      }
    },
    "Shadow": { "castShadow": true, "receiveShadow": false },
    "CarDrive": {
      "maxSpeed": 34,
      "acceleration": 16,
      "braking": 26,
      "steerRate": 2.4,
      "grip": 0.8,
      "keyboardControlled": false
    },
    "ContactDamage": {
      "targetTag": "player",
      "damage": 2,
      "radius": 4.2,
      "repeatDelay": 0.6,
      "minClosingSpeed": 8,
      "speedScaling": 0.4
    },
    "Health": { "hp": 4, "maxHp": 4 }
  }
}

Every slot in that pool carries a ram profile aimed at the player tag. Give the player the mirror image of it, plus something to lose:

"ContactDamage": {
  "targetTag": "enemy",
  "damage": 1,
  "radius": 4,
  "repeatDelay": 0.6,
  "minClosingSpeed": 10,
  "speedScaling": 0.35,
  "selfDamage": 1
},
"Health": {
  "hp": 24,
  "maxHp": 24,
  "invulnSeconds": 0.4,
  "respawnPosition": [0, 0.5, 0]
}

radius is centre to centre, so it wants to be about the sum of the two bodies' half-lengths: a 4-deep car meeting a 4.4-deep one touches at roughly 4, not at 1. And targetTag is what keeps the blue cars scenery — they are tagged traffic, so neither side of that pairing is willing to hurt the other.

With the enemy pool now in the scene, put Traffic.RoadSpawner.enemyChance back to its shipped 0.35. Roughly a third of the spawns come out of the red pool.