The basic underpinnings of a gas bbq are really quite simple: First come burners to create heat. Above them you'll find some type of system to disperse the heat from the burners (Flavorizer bars, ceramic briquettes, lava rock, etc.). Above those lie the cooking grates. Let's look under the hood to get a better sense of what you should be looking for.The Cooking System
Better barbecues generally have two or more separate burners (not just control knobs) which allow greater control of heat. Most lower-priced bbqs have only one burner shaped like an H or a bar, some with one control, some with two controls. Barbecues with one burner don't allow you to control heat as well as bbqs with multiple burners and may result in hot and cold spots on the cooking surface.
When cooking on a gas bbq, juices from the food drip down and accumulate near the heat source until they reach a flash point and burn off. The best systems quickly flash the drippings, eliminating flare-ups and creating flavorful smoke. Most manufacturers rely on lava rock or ceramic briquettes to distribute the heat from the burners to the cooking surface. Drippings from the food tend to pool in these systems causing undue flare-ups. The best barbecues use a steel bar system (pioneered by Weber) that funnels the grease away from the burner flames, greatly reducing flare-ups.BTUs (British Thermal Units)
BTUs are not a measure of cooking power. They indicate the volume of gas a bbq can burn. Tightly engineered barbecues use fewer BTUs and cook food more efficiently. Sometimes less is more. Too many BTUs can cause damage to burners and reduce the life of the barbecue. In general, large bbqs with large cooking surfaces require higher BTUs.Solid Construction
A good, well-built bbq will feel solid and sturdy; a poorly made barbecue will wiggle. If a bbq isn't solid on the sales floor, chances are it will fall apart rather quickly on the patio or deck. Choose a barbecue made of high grade U.S. steel. Also opt for a baked-on, porcelain-enamel finish. The cart should be sturdy, wheels should roll easily, and the bbq should display a good fit and finish.
Cooking grates are generally made from heavy-duty plated steel or chrome-plated aluminum. A thicker, heavier-gauge cooking grate will last longer and distribute and retain heat better. Grates coated with porcelain enamel are a common step-up feature. The best grates are made of cast iron, stainless steel, or porcelain-coated aluminum or cast iron.Assembly
When you buy a barbecue, you want to grill, not drill, so fast and easy assembly is a priority. Some bbqs require hours (and an engineering degree) to assemble. Better brands reduce or eliminate the amount of assembly required by the consumer.Service & Maintenance
Top-notch after-market service supports any quality made barbecue, including thorough, easy-to-read information about the product, and a toll-free service line. A good bbq is easy to clean and to maintain, and long-life is assured by easy access to replacement parts and service through a well-established servicing dealer network.Safety
A good barbecue lights effortlessly, controls heat easily, has handles that stay cool to the touch, and has added safety features.Long Warranty
It makes sense: the best manufacturers can afford to stand behind their products.Added Conveniences
Optional side burners are great for cooking sauces and other dishes. Flip-up side tables give you extra space for food preparation.