In support of your statement, in comparison to gasoline, diesel costs less to produce, it has more energy per unit of volume, it is much safer to store and use, diesel engines produce more torque at lower RPMs, and yes, vehicle maintenance is less costly over the length of ownership for the vehicle.
Nowadays with turbos, injectors, particle filters (required in Europe from 2007) and other fiddly bits, it's not clear that diesel engines have an advantage.
The particle filters are especially kludgy - most rely on having fuel injected down the exhaust pipe to burn the trapped cinders and regenerate the filter. If you don't run the engine long enough at 2000 rpm or so (to get the right temperature), you may clog the filter and need an expensive replacement.
(Worse yet, some designs just use the engine fuel injectors at the "wrong time" to get the piston to expel fuel down the exhaust pipe. This can contaminate the engine oil with diesel fuel and cost a few thousand in repairs, as a colleague learned the hard way ...)
