Personally I find the sentence to be realistic. "In the ditch beside the road, right side up, but violently shorn of one wheel, rested a new coupe which had left Gatsby's drive not two minutes before..." It is talking of what happened to the car, in an honest way therefore humorous and mocking would not fit. Symbolic would have words which stand for something else which it does not include, poetic would have a rhyme scheme and magical would have more whimsical figurative language.
Hope this helps! If you need more help or would like further explanation just let me know! :)
