The short answer
Proportionally, yes, and it surprises people. A Clydesdale is one of the largest horses you can own, yet pound for pound he is one of the cheapest to feed, because draft breeds were built to work hard on the forage a farm could grow. Most Clydesdales hold excellent condition on good hay or pasture with little or no grain, and feeding one like an equally tall thoroughbred is a fast route to a very fat draft. Easy keeper, in this breed, means efficient engine in a huge frame.
Draft metabolism
Clydesdales were developed in Scotland to plough, haul and work all day on oats, hay and grazing produced on the farm itself, in a cold climate that punished wasteful animals. The result is a horse with a steady, thrifty metabolism and a large, unhurried digestive system that extracts a great deal from fibrous feed. Where a hot-blooded horse burns nervous energy standing still, a draft conserves. That calm economy is the same trait that makes the breed so placid to handle, and in the feed room it translates directly into smaller concentrate bills than his size would ever suggest.
Scale changes the maths
Efficient does not mean small quantities. A horse standing seventeen hands and weighing around a ton simply has a great deal of body to maintain, and his daily forage intake, several full nets or a substantial share of a round bale, is large in absolute terms even though it is modest for his size. Winter increases it further, since forage digestion is also how a horse generates warmth. Plan storage, delivery and mucking-out around that volume before you buy: the hay bill is reasonable per pound of horse, but you will be handling a lot of pounds of hay, and a lot of what comes out the other end.
The feeding mistakes draft owners make
The classic error is grain. New owners look at the size of the animal and reach for big feeds, but most Clydesdales in light and moderate work need forage, water, a mineral source and little else; grain is added for genuinely heavy work, late pregnancy or a horse who is actually losing condition. The second error is judging condition by eye, because a draft's sheer mass and thick winter coat hide both ribs and fat pads. Learn to assess him by hand, feeling over the ribs, neck and quarters, and adjust hay gradually when your hands tell you he is gaining or slipping.
Running the routine
Consistency suits a draft: regular hay rounds, steady access to water in vessels big enough for a horse who drinks deeply, and condition checks on a schedule rather than when someone remembers. Because several people often share the care of a yard horse, write the amounts down and make the checks somebody's named job. KinsLe's Care Teams keeps exactly that discipline for a Clydesdale, with hay rounds, water checks and the hands-on condition assessment assigned as standing duties and timestamped when done, so an efficient horse is fed efficiently and never generously by accident.