HOUSTON -- Cab drivers like D. Brown and Hector Sansores watch the price of gas more than most people. 

"I fill up once, maybe twice a day," said D. Brown, Houston taxi driver.

When paying $2.95 or more a gallon, you hope to get what you pay for. But that might not be the case if you live in Houston.  According to a report from the Government General Accounting Office, the energy content for fuel that has a temperature of 90 degrees is less than fuel that has a temperature of 60 degrees.

This means that because Houston has hot weather, the lost fuel due to the increase in temperature is approximately a dollar every time a customer fills their tank.

"That doesn't seem like much, but if I work 6 days, that's six dollars. I don't even want to do the math. It will bug me," said Hector Sansores, taxi driver.

Heat causes fuel to expand and the size of a gallon is based on it being 60 degrees. Consumers currently cannot determine before or after a purchase the actual best price for a gallon of gas because they do not know the temperature of the fuel, the General Accounting Office said.

But according to the report, what angers consumers even more is that the petroleum industry often adjusts for temperature related changes in wholesale transactions for gasoline.

"They make a profit of the dollar that we are wasting," said Sansores.

"They winning both ways really," said Brown.

Gas retailers argue that the 'fix' would cost too much to justify the expense.  They said to retrofit one pump would cost about $2,000.

States can require retailers to account for the effects of heat, and Texas did consider it last legislative session.

"They should require it. They should enforce it," said Sansores.