Pass onClick handler and prevent default behavior of button in React

I am new to React/Next development. I have the code below:

import React from "react";

const Car = () => {
  var carCounter = 0;

  function addCar(event) {
    event.preventDefault();
    carCounter++;
    console.log(carCounter);
  }

  return (
    <form>
      <span className="car">
        <button class="big-button" onClick={addCar()}>
          Add Car
        </button>
      </span>
    </form>
  );
};

export default Car;

Obviously, this code is simplified. The root of my error was that the form was submitting when I pressed the button. However, the purpose of the button was to not "submit" the form. Rather, it was to increment a counter.

This is the error that was thrown above:

TypeError: Cannot read property 'preventDefault' of undefined

I went based of this thread:

https://stackoverflow.com/questions/39809943/react-preventing-form-submission#:~:text=Simply%20add%20onSubmit%3D%7BhandleSubmit,stop%20the%20default%20submission%20behavior.

Let me know what I can do!