Next a table of 'firms in business' and business failures. Nothing special in '38 here.
How about WPA and CCC? Those were the main conduits for "stimulus". This table shows thousands of participants. CCC highlighted in green, WPA in red. CCC held steady during this time. WPA went down in '37 because the economy was improving, then back up in '38 to compensate for the decline. Doesn't look like "failure to stimulate", and the families who needed the WPA weren't going to buy a new car in any case.
Next a table of total wages. Note the highlighted row of wages indexed to pre-crash 1929. It looks like '37 was an outlying positive blip, with '38 returning to slightly above '36.
Finally a more detailed table of income. Same picture: fallback from '37, but still above '36.
None of this would seem to account for the cut-in-half auto production. Banks halting loans would explain it.
The current icon shows Polistra using a Personal Equation Machine.