25 gallons.
The gas tank on the 2003 Chevrolet Express holds 31 gal..
The gas tank on the 2003 Chevrolet Malibu holds 14.1 gal..
The gas tank on the 2003 Chevrolet Corvette holds 18 gal..
The gas tank on the 2003 Chevrolet Impala holds 17 gal..
The gas tank on the 2003 Chevrolet Suburban holds 31 gal..
The gas tank on the 2003 Chevrolet Tahoe holds 26 gal..
The gas tank on the 2003 Chevrolet Express-Cargo holds 31 gal..
The gas tank on the 2003 Chevrolet Silverado-1500 holds 26 gal..
16 gallons
A Chevrolet Cobalt can hold approximately 13.9 gallons of gas.
26 Gallons (From the Chevrolet website)