Indy 500 race cars are running on 100% renewable fuel and tires with recycled plastics

The green flag that starts the Indy 500 scheduled for Sunday, May 28, holds extra significance this year: The 33 open-wheel cars will be the cleanest, greenest and potentially meanest in the 107-year history of the classic American race.

Indy cars will be burning 100 percent renewable biofuel, using carbon neutral motor oil and orbiting the oval on tires made of recycled plastics. Even some of the support trucks delivering supplies to the track will be electric-powered.

The new fuel blend — when its entire life cycle from production to exhaust is taken into consideration — reduces greenhouse gas emissions by 60 percent over fossil fuels, according to Shell USA, which supplies race fuel to IndyCar. The fuel blend is perhaps the biggest contributor to this effort that thrusts the NTT IndyCar Series into the lead in cleaning up American motorsports.

It's also part of Penske Entertainment's companywide commitment to reduce its environmental impact. Penske owns the NTT IndyCar Series and has owned Indianapolis Motor Speedway since 2019.

For the first time, the Indianapolis 500 will see all cars run on a fuel created from 100 percent renewable feedstock. For now, Shell is keeping its recipe a secret. Last year, Indy cars ran on 100-octane fuel made from 85 percent ethanol derived from corn and 15 percent racing gasoline.

Shell said this season's IndyCar fuel remains a 100-octane E85 blend. But the source of much of that 85 percent ethanol has changed. It now contains what Shell calls "second-generation" ethanol, which is made from a part of sugar cane that would have been tossed into landfills. The other 15 percent, the part that replaces last year's fossil fuel racing gasoline, is made from a nonfood source Shell won't identify. The new fuel is designed to cause little if any disruption to the race teams.

"One of the challenges is how can we develop a 100 percent renewable race fuel without asking the manufacturers to significantly alter the engine infrastructure," Bassem Kheireddin, technology manager, motorsports, for Shell Lubricants, told Automotive News.

This year, two 2.2-liter twin-turbo V-6 engines will power Indy cars, one made by Honda, the other by Chevrolet. Both often run at the limit — 12,000 rpm — cranking out more than 750 hp as they reach speeds topping 230 mph on the 2.5-mile oval.

Shell chemists worked side-by-side with Honda and Chevrolet engineers in developing the new fuel, Kheireddin said. Testing in engines on dynamometers and under race conditions in Indy cars started more than a year before the fuel's debut in March at the start of the NTT IndyCar season.

Even small changes to the fuel burned in race car engines are a big deal. Engineers must ensure that every component the fuel touches, from the rubber bladder fuel cells to the engine's intake valves, is compatible with the new blend.

"We do a full engine life [test], what you'd expect to see on the track, and then we do a full teardown," said Wayne Gross, Honda's manager for trackside support and large project leader. "We inspect the top end, bearings, everything. You look at everything that's exposed to fuel — from inside the fuel cell and all the hoses, rings and seals, fuel pumps and filters — to ensure compatibility."

Different fuel can affect races in other ways as well, including changing drivers' refueling strategies, especially if the new fuel doesn't contain as much energy as the old fuel. Because ethanol has less energy than gasoline, it's reasonable to assume the new blend — which has no gasoline — would affect fuel economy and cause drivers to pit more for refills.

But that has not been the case, Rob Buckner, General Motors' IndyCar program manager, told Automotive News. The transition has been seamless, he said.

"Since 2012, the fuel has been based on an E85 formula, and the new fuel is pretty much a direct replacement," Buckner said. "We're three races in, and fuel really hasn't been on our minds. For the drivers, it has been transparent. It's slightly different performance, but that's because we are pushing these engines to the absolute knife edge."

Both Chevy and Honda have tweaked the software that controls the fueling and ignition systems on their IndyCar race engines, but no upgrades have been needed for internal parts and fuel systems.

"The big thing is we wanted to make sure there weren't any performance differences," said Gross. "We went through our normal testing, checking how the engine runs on the dyno, checking performance numbers and calibration differences, and then we ran the engines through durability cycles.

"The fuel passed with flying colors," he said. "It's been pretty much plug-and-play."

IndyCar fuel helps Shell develop biofuels. The 100 percent renewable fuel for the Indy 500 could serve as a dry run for a new generation of biofuels that someday replace traditional gasoline, Kheireddin said.

"Shell's investment in motorsports allows us to develop better products for consumers," he said. "We use the knowledge that's gained from the track to transfer to our roadgoing products. So while the exact formulation cannot be used in a consumer vehicle, the technology we employ in this racing fuel can be transferred successfully to our roadgoing products. The formulation will be different, because it must respect the design of the road car."

Shell is planning for what Kheireddin terms an "energy transition." That means a future in which fuels made from renewable sources are a bigger part of the menu of fuels available for different types of consumer vehicles. The company is already producing biodiesel for trucks, he said.

Bridgestone Americas Inc., which owns the Firestone brand, is making two versions of environmentally friendly tires for IndyCar races this season.

The sidewalls of the Firestone Firehawk tires that will be used in five races taking place on street tracks, such as the Detroit Grand Prix, feature a rubber made from guayule (pronounced why-YOU-lee), a woody shrub found in the deserts of the Southwest. Guayule is probably best known as a source for natural latex, used for gloves and medical devices.

Since 2012, Bridgestone has spent more than $100 million developing guayule-based rubber for tires. As with Shell's renewable race fuel, Bridgestone and Firestone chemists and tire engineers worked to make the guayule tires indistinguishable from regular Firehawk race tires.

With their distinctive greenwalls, these tires got their real-world test last year at the Nashville Grand Prix. Josef Newgarden, a two-time IndyCar champion who drives for Team Penske, didn't even notice.

"Josef Newgarden got out of the car and said, 'I don't see any difference,' " said Cara Krstolic, Bridgestone's executive director of race tire engineering and product engineering.

"So that was a great compliment that there was no difference between the two tires."

Krstolic said that tires made with guayule are more environmentally friendly in many ways.

"The Hevea tree grown on farms in Southeast Asia is where most of the natural latex rubber comes from, so that takes a lot of water," she said. "And then you have to get that material from Southeast Asia to the United States, get it processed and into our tire production process. Guayule is a domestic source of natural rubber. Now it doesn't have to come by air or boat from Asia."

Guayule requires very little water compared with Hevea, and it can grow in areas where drought and higher temperatures are common. Bridgestone grows its own guayule shrubs at a farm in Arizona, and the environmentally friendly Firehawk tires are made at the company's Advanced Test Production Center in Akron, Ohio.

Because tires are such a crucial safety component of race cars, changing from a proven rubber to a new source of rubber has risks. The surface of a tire on a Formula One race car — which is very similar to an Indy car — can reach 230 degrees. The sidewalls are under tremendous stress as the cars take corners at high speeds and often at full throttle.

For IndyCar races run on oval tracks, such as Indianapolis Motor Speedway, the second version of the Firehawk tire contains recycled consumer plastics. It is made with recycled monomers that create a synthetic rubber and it is resistant to wear.

Bridgestone's environmentally friendly race tires are part of the company's larger goal to become carbon neutral by 2050 and make tires from 100 percent sustainable materials.

"Our goal is to use more guayule in our passenger car tires," Krstolic said. "And in order for that to happen, we have to scale up our production and our processing of the material. Bridgestone has invested quite a bit of time and money in bio rubber in order to get us to the point that we are better able to commercialize it.

"The link between race and passenger tires is really strong," she said.