Gas additives

Actually, those old 'T' s would run on weed spray, if that was all you had.

 

They had to run on distillate... basically light naptha, a gasoline feed stock. Modern gasoline was too expensive for use as automotive fuel. According to this article http://automationgame.com/phpBB3/viewtopic.php?f=14&t=762 regular gasoline in 1930 had an octane rating of about 62, and that was after the discovery of the anti-knock properties of tetraethyl lead ("ethyl" gasolines). 1930 was before the discovery of catalytic reforming http://en.wikipedia.org/wiki/Catalytic_reforming around 1940 which improved the quality of gasoline feedstocks greatly, and allowed the wide distribution of gasoline with up to a 100 octane rating (equivalent to 100% of octane and 0% of the more volatile heptane). Today's regular gasoline at 87 octane (87% octane/13% heptane equivalent) back then was rocket fuel - both exotic and wildly expensive.

There's an apocryphal story that the name "Phillips 66" came from the superior octane rating of their gasoline ... 66 octane was good, high-test fuel back in 1917 when the company was founded.

 

Bear in mind the 'T' has a compression ration of 4:1. (Yet they got as much as 20mpg!)

My dad used to tell how when gas was rationed in WWII, he'd start up his cars on gas, then switch over to Kerosene once warmed up.
But he said the entire exhaust system would glow red after a while.

The Fordson tractor (1917) was actually designed to do the same thing, and was ethanol capable too. Had a vaporizor intake.

Lot of Model T DNA in our Jeeps' original development, BTW.