All you have to do to maintain better than average engine health is change the oil more often than recommended.
Modern engine/fuels burn a lot more effiecently than old cars did so the carbon build up is no way as near as big a problem as it used to be.
My dad religiously changed oil every 3 Months using a good quality cheap oil (doesn't have to be expensive). Whenever he did an engine rebuild on one of his cars it was like new on tear down even after fifteen years
Use only premium fuel and change your oil regularly and your engine will out last the car for normal everyday use. Good oil health = good engine health.
Interesting discussion here:
http://www.techsupportforum.co ... nge-frequency-114349.html
Driving your engine to its limits to 'clean' it is a myth imo it may have an effect but to say it is better than or replacement to good engine care is not a good idea. If you do a lot of city driving it can do it good to take it on a long country run but doesn't have to be driven at its limits, pushing an engine to its limits increases engine wear and may blow out a few cobwebs but that is only if the engine hasn't been cared for properly in the first place.