Clark, of Scotland, had set pole in 1964, again started from the front row, and led 190 laps, the most since Bill Vukovich (195) in 1953.

After suffering a terrible crash in January at the Motor Trend 500 at Riverside, A. J. Foyt was back behind the wheel in time for the 500.

Foyt had suffered a broken back, crushed sternum, and a concussion[3] after he lost his brakes, hit an embankment, and flipped violently in a stock car.

The rookie class of 1965 was historically notable, including such drivers as Mario Andretti, Al Unser Sr., Gordon Johncock, Joe Leonard, and George Snider.

Instead, USAC officials crafted several calculated rule changes to effectively encourage teams to use methanol in order to be competitive.

On-board fuel tank capacity was reduced to 75 gallons, which also included requirements that they contain rubber bladders inside.

Conventional "pump" gasoline registered better fuel mileage than methanol, and gasoline-power cars could go a longer distance before needing to refuel.

Prior to 1965, the typical strategy of the gasoline-powered cars was to make one scheduled pit stop for fuel at some point after the halfway mark (lap 100).

Ideally, the pit stop would come around lap 120–125 (of 200), meaning the crew needed only to refill the tank at that point about 3⁄4 full to make it to the finish.

Methanol-powered cars in general needed to make 2–3 pit stops to complete the full 500 miles, even before the rule changes.

Chief mechanic Johnny Pulson and driver Parnelli Jones determined that they were effectively down on power, finished second, and attributed the fuel blend as what cost them a chance to win the race.

Prior to 1965, no draw was used, and the qualifying order was a "first-come, first-served" line-up, queued down the pit lane and usually stretching into the garage area.

The unorganized scramble to roll the cars into a queue had often led to heated exchanges, collisions, and unfair situations.

A proposal to charge cars with an attempt if they got to the front of the line but elected not to go out, or went out and did not take the green flag to start the run, was rejected.

Defending race winner A. J. Foyt ended up as the fastest of the day, with three laps in the 161 mph range.

A day after his crash during practice, Bobby Unser got in a year-old Novi back up car to qualify 8th.

Bobby Johns, a NASCAR regular, skipped the World 600 and entered as a teammate to Jim Clark in another Lotus.

Bob Mathouser was the final driver in Indy history to attempt to qualify in a front-wheel drive machine, but the engine blew and he did not make the field.

[16] The Wood Brothers from the NASCAR Grand National circuit, were invited by Ford Motor Company to work the pit stops for Team Lotus (drivers Jim Clark and Bobby Johns).

They were well known for their rapid pit stop work in NASCAR, and their presence immediately created a stir in the garage area.

[20][21][22] Historians agree that Clark's Lotus-Ford was capable of winning the race handily without the added help of the Wood Brothers.

[23] Clark made only two stops all day, and the quickness of the refueling process was largely attributed to a specially-designed gravity fueling rig with a venturi tube.

The lone accident of the day involved Bud Tingelstad, who lost a wheel and spun into the outside wall in turn three.

Second place Parnelli Jones ran out of fuel on the final lap, and pushed his car back to the pits.

Fred Agabashian served as "driver expert," and Rodger Ward (who failed to qualify), joined the pre-race coverage briefly to offer commentary.

Foreign translation rebroadcasts in Spanish, Portuguese, French, and Italian were heard in Central and South America and elsewhere.

After visiting the broadcast booth in 1964 for an interview, Donald Davidson returned, joining the crew full-time as race historian.