I shoot manual all the time, but it's crazy to imagine that I'm getting different results than I would shooting in an automatic mode. Either way, the camera will suggest an exposure, and I will take that suggestion into conisderation but end be overriding the camera's suggested exposure a fair amount of the time. The only difference is *which* situations would require me to override the camera's suggestion, and the specific buttons I'd have to push in order to do the overriding. For me, I find that the way this works in M mode fits the way I think better than the way it works in other modes - plus it means I don't have to change my thinking every time I mount an "M" lens.
Now, if you're saying you always shoot in av mode and never ever see the need to use exposure compensation, or meter off one scene and lock exposure then recompose to shoot a different scene, or change to spot metering to meter off a specific subject, I'd say you're missing out on a lot of creative control. But you can exercise that control from Av mode as surely as you can from M - the process is just different.
For instance, you mention shooting at a car show. Ever shoot a closeup of a white car? How'd that exposure come out in "full auto", "point and shoot" mode? If your camera is functioning correctly, it would have come out medium gray. Presumably you took the necessary steps to avoid that.
BTW, it doesn't really take extra time to use M mode. Set aperture using the dial just like in Av mode. Hit the Green button to set a shutter speed - which takes an extra *fraction* of a second - and you're good to go. And no need to keep hitting the Green button before every shot, unless the light changes. That's why *I* like M mode better - I only have to take an explicit act to alter the exposure when the light changes, and I'm pretty good about noticing the light change (plus I watch the meter in the camera). Whereas in Av mode, you have to change the amount of exposure compensation every time you go back and forth between shooting a white object and a black one. I reckon "M" mode involves *less* button pushing overall, because light doesn't change as often as the content of the scenes I shoot does. But again, you can get the exact same results either way.
Last edited by Marc Sabatella; 01-30-2009 at 08:43 PM.