The existence of a thing in dependence of its causes (except in the special case where we were involved in making it ) appears totally objective and does not require our participation. The causes of a car are the geological processes which produced coal, iron and copper ores. Then the miners, metalworkers, designers, component manufacturers and assembly line workers who transformed the raw material into the finished product. Unless we happen to work in one of these industries, the causal mode of existence does not depend on our participation.
Existence in dependence on parts is more subjective. We may view a car as composed of a chassis, an engine and four wheels. Or we may take a more detailed view with the engine being seen as pistons, cylinder-head, carburettor etc. These too can be analysed into subcomponents, all the way down through atoms of iron and carbon, to the fundamental particles such as protons, electrons and the photons which shine from the headlamps.
Our perception of dependence upon parts is very much determined by how we choose to subdivide the whole. The mind has to participate by applying analytical effort to generate the view of existence in dependence upon parts.
It's when we get to the final stage of perception of dependence in terms of the fundamental building blocks of matter that we come up against the very subtle (most participatory) level of dependent relationship of imputation by mind. Experiments in quantum physics seem to demonstrate the need for an observer to make potentialities become real.
Now, fundamental particles such as electrons and photons do not have any obvious causes. Either they always have been there or else they come into existence as the result of random quantum events. Neither do they have anything in the way of observable parts (otherwise they wouldn't be fundamental). So when we examine an electron or photon, we are looking at a phenomenon in which the two grosser ways of existing are relatively inapparent. As the two grosser levels are not clamouring for our attention, Kadampa metaphysics would predict that the very subtle level of dependent relationship (in dependence of imputation by mind) should manifest itself.
It is important to emphasise that the mathematical equations of quantum physics do not describe actual existence - they describe potential for existence. Working out the equations of quantum mechanics for a system composed of fundamental particles produces a range of potential locations, values and attributes of the particles which evolve and change with time. But for any system only one of these potential states can become real, and - this is the revolutionary finding of quantum physics - what forces the range of the potentials to assume one value is the act of observation. Matter and energy are not in themselves phenomena, and do not become phenomena until they interact with the mind.
[KELSANG GYATSO 1992] The First Panchen Lama, cited by Geshe Kelsang Gyatso in Clear Light of Bliss, 2nd Edition page 146 (London :Tharpa Publications, 1992, ISBN 0 948006 21 8).
[CONZE 1959] Conze, Edward (tr) Buddhist Scriptures p 146 ff; (Harmondsworth, UK: Penguin Books Ltd , 1959)
[BROOKES 1999] Brookes, Martin, Live and Let Live , New Scientist p 32 -36, 3rd July 1999.
[LOY 1996] Loy, David in the afterword to Swedenborg, Buddha of the North , page 104, (Swedenborg Foundation, West Chester Pennsylvania, 1996, ISBN 0-87785-184-0)
[KELSANG GYATSO 1995] Gyatso, Geshe Kelsang, Joyful Path of Good Fortune, 2nd Edition - page 349, (London: Tharpa Publications, 1995, ISBN 0 948006 46 3)