We seem to be using different understandings of intrinsic value. The subjective value something has in a particular situation is its extrinsic value. The intrinsic value is the objective value that that thing has in itself, or in its own right, i.e. its fundamental properties that can be objectively measured, things that are not dependent on market demand, user preference or sentiment.
For the Porsche that would presumably inhere in the amount and quality of the materials it is made of, the workmanship, the construction, functionality, its performance, economy, etc. For the glass of water, likewise, the quantity and quality of the glass, the design & functionality, the amount and suitability of the water for drinking, and so-on. There are some philosophical issues about precisely what constitutes intrinsic value (e.g. distilled water is not great drinking water, so does the intended purpose count?), but it's the principle that matters.
Yes, energy quantifies an intrinsic property equivalence. Rearranging the molecular binding of a certain amount oxygen and the hydrocarbons of petrol produces a predictable amount of high-frequency photons and fast-moving molecules, that produce vibrating & colliding atoms in nearby material (heat), and a local increase in the amount and velocity of gas molecules (pressure). This conversion is quantified using an indirectly observed abstract conserved property called energy.
Molecular binding energy, light energy, thermal energy, kinetic energy, gravitational potential energy, etc., are the names we give to the values of certain properties (states or contexts) of stuff, using a common unit that we use to quantify the conversion between those properties.