Why can't I get that grilled taste from my outdoor grill?

Based on your updated question, the major factor is that your fire simply is not hot enough to produce the charring and browning reactions you desire.

A steakhouse salamander (think of a broiler—grill in British parlance—which has flames on both the top and the bottom, to cook both sides at once) can be up to to 1000°F and the elements are mere inches from the steak on both sides.

Gas grills have a maximum amount of heat they can produce. The only thing you (may) be able to adjust is the distance to the flame. The major cooking modality in a grill is infrared thermal radiation. This decreases per the square of the distance, so the closer your food is to the burner, the faster it will cook (within reasonable limits).

Other than that, you may need new equipment if this is in fact the root cause of your issue.

The key to getting good flavor out of a gas grill is very thorough preheating. You want your grill to reach temperatures upwards of 500-600 degrees Fahrenheit, at least. Your grates don't need to be glowing, per se, but they should be very, very hot.

If you're cooking burgers or steak, you shouldn't need to turn the heat down below medium. In fact, if you cook your burgers uncovered, then you can leave the temperature at the highest it'll go the whole time. This does use more gas, though, which is why most people put the meat on the very hot grate, then turn down the heat and close the cover.

Chicken, especially bone-in chicken¹, is a different matter; you will have to turn down the heat, and/or use indirect heat (turn on a heating element on the opposite side from where your meat is), otherwise you'll end up with raw chicken coated in cinders.

¹_{Personally I don't cook bone-in chicken on the grill, because it's just so hard to get it cooked through properly, and there are so many better ways to cook it. (It's like, yeah, you can use your grill to cook pasta, but why would you? Unless of course there's a power outage or something...)}

If you have a very low-end grill, it may not be capable of putting out enough heat to achieve the preheating temperature you want. Check out some grilling cookbooks, they will usually have guidelines on BTU's and such.

Well if its a gas grill it won't get that same taste. Charcoal grills are really good for achieving that smokey taste. But if you already have a gas grill this may help. http://bbq.about.com/od/grillingfaq/f/f070104d.htm

In case the food requires more energy to burn, you may need to worry about the quantity of food to cook at any particular moment in gas grill. In infrared grill it has the capability of cooking anything. It also sees that food can be cooked at different temperatures without adding more fuel in case the food requires more energy to burn. This also makes it the best in searing meat. But they are quiet expensive and helps in cutting down the cost of energy being consumed.