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You need to retain your own attorney to review the facts of your case with you, including reviewing the recorded easements and any agreement incident to that. If you (and your neighbors) hold a right-of-way easement, that allows you (and your neighbors) a right of ingress and egress through the servient tenament. An easement does not make any of you the owner of the road, nor does it give you the right to disturb the occupants of the servient tenament, such as speeding on the road. A right-of-way easement is typically limited to the defined portion of land, so the owner of the servient tenament would be within her/his rights to prevent you from driving outside the easement road. (In fact, if you driver over any other portion of the land, you are trespassing and the land owner can sue you). Be sure to consult your own attorney to protect your legal rights.
I doubt you can get your neighbor to remove the bumps entirely although that will be a fact intensive question probably only answerable if you proceed through judgment. If the bumps are reasonable under the circumstances – IMO a court will allow them to stay unless they are a clear violation of a written easement. The boulders on the side of each bump, on another persons property, are allowed if your easement does not extend to that portion of the land.
A quick search of CA case law didn’t reveal any appellate opinions published on this particular issue although my search could be incomplete.
If you retain counsel, and if the individual who installed the bumps has insurance, you may be able to obtain a reasonable settlement sum for any alleged damage to your sports car and/or have them reduced in size to avoid damage in the future. If you decide to make a claim against your neighbor you should, however, make certain your own homeowners' insurance is paid-up and that you are fully insured for liability as claims beget claims. In many cases, involving insurance companies in disputes such as these allow for a favorable resolution among the parties.
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