The government's plan to blend petrol with ethanol is supposed to chip away at Zimbabwe's huge fuel import bill, but it has car owners worried.
The government has ordered that all fuel sold must be blended with 10% ethanol (E10).
The country uses up to two million litres of petrol a day and imports nearly $2-billion worth of fuel each year.
The government says that blending petrol with ethanol will cut the country's fuel bill by at least $4-million a month.
Much of that demand is driven by the flood of second-hand Japanese cars into the country, which amounts to about $1-billion each year, according to data from the treasury.
Car owners will have no choice and the government is apparently planning to increase blending levels higher than E10, which is raising fears about possible damage to vehicles.
"This label clearly states what fuel is recommended for my car. What's this E10 stuff?" a driver said to a petrol attendant this week, pointing to the "unleaded petrol only" instruction on his fuel tank cap.
Green Fuel, an ethanol plant at Chisumbanje, is producing 300 000 litres a day and the company is ramping up production.
Green Fuel general manager Graeme Smith has told local media that other countries in the region have shown interest in it.
"In the next seven years we will be producing 500-million litres of ethanol per year. The 500-million litres would be enough to substitute the country's petrol requirements by 100%."
When the Green Fuel blend first came on to the market as an option to unleaded fuel, sales were poor because of fears about its safety.
The result was that Green Fuel found itself with more fuel than the market wanted.
Assuring motorists of safety
However, after putting pressure on the government, and reportedly promising to fund farming in return, the government agreed to mandatory blending and the factory, which had been shut down, was reopened.
The Zimbabwe Energy Regulatory Authority (ZERA) has been working hard to assure motorists of E10's safety but it wants to raise the blending level to as much as 20% by March.
"Studies have already been done by reputable and internationally recognised institutions. Most of the studies are applicable to the vehicle models used in Zimbabwe, including imports," Gloria Magorimbo, the head of the ZERA said.
But Green Fuel wants it to be increased further. "If, for example, E85 is adopted, this will translate to a saving of 40 US cents per litre on fuel costs by individual motorists," Smith said.
However, experts say only modern flexible-fuel vehicles, also called FFVs, of which there are very few in Zimbabwe, can take E85. Even in the United States less than 10% of the vehicles are FFVs.
The promised drop in fuel prices that ethanol would bring has also not been as large as widely expected, and Magorimbo acknowledges there would only be a "marginal drop of two to three cents" in fuel prices.
More bad news for motorists
A recent report quoted Toyota Zimbabwe's principal dealer, Simplicio Shamba, as saying that raising blending to E20 would damage older vehicles.
"We have written to government advising them that most of our vehicles are compatible up to E10 blended fuel," Shamba was quoted as saying.
More bad news for motorists is that ethanol delivers 33% less energy than petrol, which means that cars will use more blended fuel. With such a small difference in price, this means that blended fuel could, in fact, cost motorists more.
An expert, who did not want to be named, also said E15, for instance, "would corrode metal and rubber components in older engines".
He pointed to a recent study by US vehicle manufacturers that found that 25% of cars approved by the Environmental Protection Agency to run on E15 experienced damage and failure.
There is also concern about what increased investment in green fuel will mean for food production.
Price of maize
In the US one of the effects of the rise in ethanol production has been a rise in the price of maize, which is widely used for ethanol production. Since 2005 maize prices have gone up by 65%.
In Zimbabwe, Green Fuel has taken over large tracts of land to grow the cane needed to feed its factory. Villagers in the affected areas are split over this.
Some are opposed to the use of land to grow cane instead of food, but many have welcomed the economic benefits of being Green Fuel growers.