No, sorry, not cheaper gas. For the rest of the year, the IRS (US) has raised the standard mileage rate from 40.5 cents to 48.5 cents per mile. This went into effect on September 1, 2005 and will continue until December 31, 2005.
The 8-cent increase is due to gas price hikes — no surprise to you, right — and comes after what had already been the largest one-year rise ever from 2004 to 2005. The IRS had attributed the first increase in the standard mileage rate from 2004 levels at least in part to higher fuel costs.
No real relief here, but it will help on your small business taxes. Make sure you keep track of your mileage so you can get the credit you deserve.