Motorists, start your engines. It's opening day for the last leg of a Texas toll road with the nation's fastest speed limit. The final 41-mile stretch of Texas Highway 130 will open today after three years of construction. The speed limit will be 85 mph. The toll road is intended to help alleviate the increasingly crowded Interstate 35 corridor between Austin and San Antonio, which are two of the state's largest metropolitan areas. The new stretch will be from Mustang Ridge, about 10 miles south of Austin's international airport to Interstate 10 just east of Seguin. A 50-mile stretch bypassing Austin is already open. Tolls for personal vehicles displaying an electronic toll tag will be about 15 cents per mile. But no tolls will be collected until Nov. 11.