假设您使用的是make:entity命令：如果您将cars属性添加到您的Suggest实体，并使其成为Car的ManyToMany关系，它不会将额外的属性添加到Car类（您可以对该类说no）：
Car：

<?php

namespace App\Entity;

use App\Repository\CarRepository;
use Doctrine\ORM\Mapping as ORM;

/**
 * @ORM\Entity(repositoryClass=CarRepository::class)
 */
class Car
{
    /**
     * @ORM\Id
     * @ORM\GeneratedValue
     * @ORM\Column(type="integer")
     */
    private $id;

    public function getId(): ?int
    {
        return $this->id;
    }
}

以及Suggest：

<?php

namespace App\Entity;

use App\Repository\SuggestRepository;
use Doctrine\Common\Collections\ArrayCollection;
use Doctrine\Common\Collections\Collection;
use Doctrine\ORM\Mapping as ORM;

/**
 * @ORM\Entity(repositoryClass=SuggestRepository::class)
 */
class Suggest
{
    /**
     * @ORM\Id
     * @ORM\GeneratedValue
     * @ORM\Column(type="integer")
     */
    private $id;

    /**
     * @ORM\ManyToMany(targetEntity=Car::class)
     */
    private $cars;

    public function __construct()
    {
        $this->cars = new ArrayCollection();
    }

    public function getId(): ?int
    {
        return $this->id;
    }

    /**
     * @return Collection<int, Car>
     */
    public function getCars(): Collection
    {
        return $this->cars;
    }

    public function addCar(Car $car): self
    {
        if (!$this->cars->contains($car)) {
            $this->cars[] = $car;
        }

        return $this;
    }

    public function removeCar(Car $car): self
    {
        $this->cars->removeElement($car);

        return $this;
    }
}