TotalFlex Capabilities

Volkwagen Gol sets shining example for flex-fuel vehicles, running on any blend of ethanol up to E100 in Brazil.
By Susanne Retka Schill | January 15, 2015

The Volkwagen Gol is a subcompact with admirable capabilities. It runs on any blend ethanol up to E100, automatically adjusting the engine for differing blends. Plus, a unique system solves the problem with cold starts on straight ethanol. VW calls it a TotalFlex vehicle. Unfortunately for U.S. ethanol supporters, it’s only available in Brazil and handful of neighboring countries.

John Voelcker is one American who’s gotten a close look at the Gol. The editor of Green Car Reports, he test-drove the Gol in Brazil. “Given that this was a smaller and simpler vehicle for an audience that is less demanding in some ways than wealthier North American buyers, I was curious to see if there were compromises,” he says. “I couldn’t find any. It behaved exactly as I expected it to. The responsiveness, the engine behavior did exactly what it should do. There was no stumbling, none of that—it’s a perfectly modern car that was able to accommodate different liquids in its tank. I think that’s a huge accomplishment.”

In writing about his trip to Brazil to test drive the Volkswagen, Voelcker told his readers, “While many North Americans may not know it, Brazil presently leads the world in deploying biofuels for road vehicles. Specifically, a majority of cars sold in Brazil—especially lower-price, high-volume models built in the country—can run either on gasoline or pure ethanol.” 

That wasn’t always the case. “Brazil has had two waves of ethanol cars,” Voelcker tells Ethanol Producer Magazine. “The first ones in the late ’70s and early ’80s were pretty substandard compared to today’s cars and to gasoline cars at the time.” Most used carburetors or poor fuel injection systems when compared to today’s fuel injectors that benefit from 30 years of improvements in computer software, microprocessing speed and sensors, he explains. “You couldn’t have made the car we have today, 30 years ago. Those cars were only ethanol, they weren’t flex fuel.  Wave two has been flex fuel, which in the states we define as E85 but in Brazil can be up to E100.” The base fuel in Brazil is anywhere from E20 to E25, he adds. “I didn’t ask about G100 [straight gasoline], because it wasn’t relevant.”

When Brazil adopted stricter emissions controls, VW moved away from carburetors to fuel injection and catalytic converters. “That technology enabled the flex-fuel capability, but still they’re doing it as inexpensively as they can, while maintaining reliability,” he explains. “The goal was to make a car that could run on gasoline or ethanol or any combination of the two without the driver really noticing. What has enabled that is modern sensors and engine control software.”

 “Modern emissions control equipment on engines is really remarkably sophisticated,” he continues. “You have three-way catalytic converters that monitor each combustion cycle, in effect, and adjust on the fly.” The current Gol can discern what fuel is coming into the engine and adjust its combustion programming accordingly. “Two lambda sensors in the exhaust system—one before the catalytic converter, one after—continuously monitor the oxygen content of the exhaust. Their input lets the engine-control system choose one of roughly 2,000 different combustion maps to optimize power, smoothness, and fuel efficiency. And the car remembers what fuel it has in its tank, so it effectively resets its engine programming after each fill-up.”

The first wave of ethanol cars were known to be temperamental starters in cold temperatures, and most included a small, ancillary gasoline tank for cold starts that consumers would forget to keep full. VW eliminated that by building a heating element directly into the fuel-injection rail. In cold weather, as soon as the driver’s door opens, the car uses battery energy to heat up the element even before the driver turns the key. It heats up the fuel enough to eliminate the problem with ethanol starts.   
A Volkswagen do Brasil spokesman explains the Gol was developed for the Brazilian market, where the lowest temperature observed is about minus 5 Celsius (23 degrees Fahrenheit). At that temperature and using hydrated ethanol, the VW Gol starts within two seconds.

Hydrated ethanol, he goes on to explain, is used for cars designed to handle E100. It contains between 4 and 5 percent water. “Obviously, this water is not burnt in the combustion of ethanol, but its presence increases the octane number of the fuel, which allows for a higher compression ratio, increasing the performance and efficiency of the vehicle. However, the presence of water also increases the corrosion of ethanol, forcing the use of stronger metals.” 

Built since 1980, the VW Gol has been Brazil’s most popular vehicle for 27 years, Voelcker reports, with Volkswagen do Brasil building more than 7.5 million.  “The one thing to remember about Brazil is that it is not as affluent a car market as the U.S., so the Gol, which is extremely popular in Brazil, is what we would consider a subcompact that does not include a number of the safety or entertainment features we would expect in even a low-priced subcompact,” the Green Car Reports editor says. “It’s a car designed specifically for Brazil and a handful of nearby markets.”

Author: Susanne Retka Schill
Senior Editor, Ethanol Producer Magazine