You are standing on your commitment to the word of God and sacrificing something to receive a blessing. Dreaming of buying could represent a spiritual exchange. You give God faith and He gives blessings.
Your motivation and ministry is about helping people to be born again. If the car was gold (which seems the more likely) then the Gold color could symbolize a ministry that enables the new believers (trees) become overcomers with holiness, wisdom, glory, and righteousness.
The garden tool represents maintaining the direct connection to our love relationship with Christ. The fact that the seats were folded down in the car indicates this ministry is not for resting but is actively preparing the hearts of people for a relationship with God or other people.
Although you have been playing a supporting role (passenger side) you have been given the authority strength and power in your hands through a new opportunity (open door) to help new people (baby trees) receive the spiritual support they need. Although the ministry is like a hedge around you to focus your attention on, but you have feelings of anger, or being irritated by nagging problems in life that you need to deal with.