I bet they wish they'd installed some rail adapters instead of testing the cars suspension for miles. Notice that the left front fender is removed, that must have been done to make it easier to steer on the Florida East Coast Overseas Railroad.

https://forums.aaca.org/topic/341211-period-images-to-relieve-some-of-the-stress/page/238/

a 41-mile stretch of railroad tracks from Lower Matecumbe en route to the Long Key Fishing Camp in 1927

The celebrated arrival of Henry Flagler and his Key West Extension of the Florida East Coast Railway was Jan. 22, 1912. Though Mr. Flagler’s railcar arrived at the southernmost terminus that day, it did not mark the day construction of the railroad was finished.

Because of his failing health, the job of bringing the train to Key West was rushed. Shortcuts were taken to hasten the project and ensure that Flagler saw his dream come to fruition. The railroad engineers were successful, and when Mr. Flagler’s railcar arrived in Key West, it did mark the beginning of daily railroad service operating between railroad depots at Miami and Key West. One of the lesser-reported stories about the railroad is that it was not officially completed until 1916.

Henry Flagler died on May 20, 1912. He never rode down to Key West aboard his private railcar on the completed Over-Sea Railroad project.

It was decimated by the Great Labor Day Hurricane of 1935 and the railroad was already in a poor state financially so they were unable to rebuild it. The state of Florida bought what was left of it and turned it into the original Overseas Highway.

https://keysweekly.com/42/keys-history-flagers-arrival-to-southernmost-city-didnt-mark-an-end-to-railroad-construction/