The only possible glitch in King’s otherwise accurate description of the car was the use of “hub caps”. If by hubcaps he meant wheel covers, 300SDs from 1978-80 came with aluminum wheels standard, not wheel covers. Of course, it’s possible it could have been retrofitted with a set of these shown here. Or it’s possible he meant hub caps as in the center cap of the aluminum wheels.
When your favorite fiction authors write about cars, do they get the details correct? (Part 1)