Since it doesn't cost anything...
Since it doesn't cost anything but time, we spent a while scraping the undercoating off our car. Again, weight reduction seems insignificant, but every ounce helps.
Replacing some of the steel outer body panels with fiberglass parts is another way we'll shave pounds from our bracket racer. Remember though, some replacement fiberglass body parts are flimsy and poorly made. While these types of replacement panels will save weight, chances are they won't fit well, and they certainly won't last through the abuses of drag racing. Knowing that we needed to find good-quality fiberglass, we called our friends at AAR Quality Fiberglass and ordered a hood, trunk lid, and both bumpers for our Barracuda. The AAR parts are exceptionally well built, with reinforcing braces molded into the underside. The finish of the AAR parts is also outstanding. the parts come ready for final sanding and paint; there is no trimming or bodywork required. By ordering a pin-on hood and decklid, we'll be able to save additional weight by eliminating the hood, trunk hinges, and latching mechanisms.
The final way we'll save weight from our car is to replace all the glass windows with lightweight polycarbonate material. The glass, especially the rear window of our fastback, is very heavy, which makes this one of the best techniques to save weight. Even if you've never fabricated and installed polycarbonate windows, you can do the job easily with tools you already have in your shop. The material is available from any home-improvement store and is easy to handle, cutting easily with a jigsaw. By using the factory glass as templates, you can replace all the glass in your race car in a weekend, shaving significant weight in the process.

After cutting and gutting...

After cutting and gutting our car to reduce weight, we added torque boxes, frame connectors, and a 12-point rollcage. While the added weight of these components isn't great for elapsed times, it is mandatory for the safety and longevity of our race car.

We replaced our trunk lid...

We replaced our trunk lid and both front and rear bumpers with AAR fiberglass components, as well. Again, the weight savings by changing these components alone is not dramatic, but in conjunction with our other modifications we reduced the weight of our vehicle by several hundred pounds.

Fiberglass body components,...

Fiberglass body components, such as the hood shown here, are a great way to shave a few pounds from your car. We love the products of AAR Quality Fiberglass in Cocoa, Florida. These pieces need no bodywork, just a quick scuffing with a Scotch-Brite pad, and they're ready for paint.
Also, don't forget about the most important type of weight: reciprocating weight. A reduction in reciprocating weight can have an exponential effect, freeing horsepower to propel the car forward. Lightweight pistons, rods, and valvetrain components all help free up horsepower in the engine, and lightweight driveline components require less power to turn, thereby putting more power to the rear wheels. Speaking of wheels, lightweight rolling stock is a benefit to any race or street car.
While we didn't weigh the items we removed from our car individually, we did weigh the car when it was completed and in race trim. On the scales, without a driver but otherwise ready to race, our Barracuda weighed 2,878 pounds. Knowing that a factory '67 Barracuda's shipping weight was approximately 2,900 pounds, we basically negated the 200 pounds of rollcage and 50 pounds of frame connectors and torque boxes, getting our car back down to its factory weight. While this doesn't sound like much, remember that every hundred pounds equals a tenth of a second, or about a car length, which could mean the difference between a win and a loss. Additionally, by reducing the weight of our car, the load on the engine and drivetrain is reduced, thereby lengthening the service life of our components.