I think it's faster to drive to everywhere except MK. That said, I think it's worth the small loss of time to use the buses. There is something about not having to get into your car and drive. That's something you do in the real world, so it takes you out of the experience in my opinion.
There is absolutely no difference between driving in WDW then driving around the city or town that you live in. It is well signed and easy to backtrack if you miss a turn, it is faster and more convenient then taking the bus and allows more flexibility then the buses do to bring stuff with you especially strollers and snacks.
Riding a bus in the real world isn't exactly what most people strive for. It is sometimes filled with tired, sweaty and grumpy people and not at all a magic moment.
We almost always have our car since my sister will not fly.....we take the Amtrak Auto Train from Virginia to Florida and back....
We use the buses to go to all the parks and save the driving for going to FW and to DTD (or whatever it is called)
Who wants to track down a car late at night after wandering around a park all day? Not me!! And sometimes the walk to the car takes quite a few steps...I am done walking at that point usually
You make it sound like while your gone they hide your car. Anyone with an IQ higher then a rock has no trouble finding their car. Everyone has a cell phone, usually with a camera, that can be used to photograph the lane and lot that you are in. As far as walking to it, well the tram takes you almost to it and it is no more hard on your feet then standing in a line waiting for the third or forth bus to arrive and take you back to your hotel at closing.
Drive everywhere, except:
Magic Kingdom
I'll drive the car to any park except Magic Kingdom. On our MK days, the car stays at the resort and we take Disney Transportation. I really, really, really hate the whole Ticket & Transportation Center experience. We always try to avoid that, and find the buses to be much less of a hassle. The only exception is when we have an early morning start, like the day we did the Magic Behind Our Steam Trains tour and had to be at the gate by 7:15 AM.
Park Hopping
The other time we might leave the car behind and take Disney transportation is days when we know we're going to be park hopping. It's usually easier to deal with the buses than back-tracking to the first park to get the car.
Booze
And finally, on nights when I know I'll be drinking, we'll obviously leave the car behind. An example of this is on our next trip when we have the IllumiNations Sparkling Dessert Party booked at Epcot. With an hour and a half of all-you-can-drink wine, I know we'll be on the bus that day.
Magic Kingdom... I don't understand why people always want to skip two of the best attractions at WDW. Either the Monorail to MK or the Ferry ride to MK. The ferry, in particular is a restful relaxing scenic ride where you can watch yourself approaching the Castle instead of being dumped off like a herd of cattle from a bus. Takes a little longer, but, not near as much as you think. The time is made up by the fact you don't have to wait for a bus to arrive. You go to the parking lot, jump in your car, crank up the AC, if necessary or the CD player and be on your way.
Park Hopping... Has never been a problem with my own vehicle. It is actually faster then the buses and it is really easy to organize especially if you are hopping between Epcot and MK. Simply park in the place that you expect to be at the end of the day. For example, if you plan to be in Epcot at closing, park there in the morning and take the Monorail to MK, returning later and then you are where your car is.
Booze... I don't mean to sound obnoxious here, but, I do not go to WDW to drink. I go there for the entertainment. I am not a teetotaler, just someone that separates one activity from another. I am lucky, I guess, I don't need booze to let me enjoy stuff.