Back in the good old days, an hour’s wages wouldn’t get you very far. Your Model T only got about 17 miles per gallon from its 20 h.p., 2.9 liter engine. If you had a good job (making Model T’s, for example) you could expect to earn about 50 cents an hour, which would buy you just two gallons of gasoline. That comes out to just 34 MPHW.
By 1935, with the Depression in full swing, wages were still pretty low and your 1935 Ford V-8 gave you even worse fuel economy than the Model T, but at least gasoline was cheaper. MPHW edged up to about 50.
After WWII, wages started to climb, pushing MPHW over 100 by 1950. For the first time, you could actually earn money faster than you could burn through it on the highway.