Then, there where the Venerable Kāmabhū was, there Citta, the householder, approached. Having approached and having saluted the Venerable Kāmabhū, he sat to one side. Having sat to one side, the Venerable Kāmabhū then said this to Citta, the householder:
"This was said, householder: 
"How, then, householder, should the detailed or expanded meaning of this condensed statement be seen?" 
"Was this, Venerable One, spoken by the Blessed One?"
"Just so, householder."
"So then, Venerable One, please wait a moment while I look at its meaning."
And then, Citta the householder, having been silent for a moment, said this to the Venerable Kāmabhū:
"'Faultless part': now this, Venerable One, is a metaphorical expression for the virtues.
"'Adorned in white': this, Venerable One, is a metaphorical expression for liberation.
"'Going one way': this, Venerable One, is a metaphorical expression for mindfulness.
"'Rolls on': this, Venerable One, is a metaphorical expression for advancing and retreating.
"'Chariot': this, Venerable One, is a metaphorical expression for this body of four great elements, produced from mother and father, accumulated out of boiled rice and grain, subject to erosion, abrasion, dissolution and disintegration.
"Lust, indeed, Venerable One, is disturbance, hatred is disturbance, delusion is disturbance. For a monk with poisonous mental influences  destroyed, these are abandoned, broken at the root, like a palm made groundless, with sprouts annihilated, such that, thereafter, they have no arising. Because of that, a monk with poisonous mental influences destroyed is called 'one who is undisturbed'.
"'The one who is coming': this, Venerable One, is a metaphorical expression for the arahant.
"'Flow': this, Venerable One, is a metaphorical expression for craving. For a monk with poisonous mental influences destroyed, this is abandoned, broken at the root, like a palm made groundless, with sprouts annihilated, such that, thereafter, it has no arising. Because of that, a monk with poisonous mental influences destroyed is called 'one with flow cut off'.
"Lust, indeed, Venerable One, is bondage, hatred is bondage, delusion is bondage. For a monk with poisonous mental influences destroyed, these are abandoned, broken at the root, like a palm made groundless, with sprouts annihilated, such that, thereafter, they have no arising. Because of that, a monk with poisonous mental influences destroyed is called 'one who is unbound'.
"Thus, indeed, Venerable One, is that which was said by the Blessed One:
"Of this condensed statement, Venerable One, spoken by the Blessed One, thus do I understand the detailed or expanded meaning."
The above translation (as well as other translations at ATI by the present translator) deliberately aims to adhere as closely as possible to the grammar and syntax of the Pāḷi text, while at the same time trying to present an easily readable English text. In this way, the translation may be especially useful for students of Pāḷi who would like to follow the Pāḷi original in parallel to the English translation.
Consequently, I would like to suggest a different interpretation, here, of ara, derived from the same verbal root from which the noun ara, 'spoke', is derived, as is the adjective ara, 'swift, speedy': namely, √ṛ, 'to go, to move' (cf. Whitney, Roots, Verb-Forms and Primary Derivatives of the Sanskrit Language, p. 14; Monier-Williams, SED, p. 223.1; Böhtlingk and Roth, Sanskrit Wörterbuch, Vol. I, p. 403.1). Monier-Williams points out a usage of ara at the end of a compound, where it has the sense 'going', and cites the example of the word samara, which is analysed into sam + ara (from √ṛ), 'coming together, meeting, confluence'; hence also 'hostile encounter, conflict, war' (cf. Böhtlingk and Roth, SW, Vol. VII, p. 689.1: sam + ar, (1) 'Zusammenlauf, Zusammenfluss'; (2) 'feindlicher Zusammenstoss, Kampf'). (It should be pointed out that Rhys Davids and Stede seem to have misconstrued the Pāli samara, 'war', as sa + mara, 'with death', i.e., 'that which is accompanied by death'.) Cone (DP, Part I, p. 232.2) cites only muddha-ara as an example ara at the end of a compound; Rhys Davids and Stede define that term as 'head (top) spoke' (PED, p. 538.2).
I propose to read ekāra as eka 'one, single, alone' + ara 'going', on the model of sam + ara. The sense would then be either: (1) that the 'chariot' (representing the Arahant) goes always alone; or (2) that the 'chariot' goes always in one direction (i.e., towards Nibbāna); or that it travels always upon one path (i.e., the Noble Eightfold Path); or that it travels only in one way (i.e., in accordance with the Dhamma). These various possible senses are not mutually exclusive, of course.
With respect to the first interpretation, ekāra as 'lone-going', which implies that the Arahant is completely unattached and lives in seclusion, we may consider that in Ud 7.5 Bhaddiya is described, as seen from afar, following closely behind the mass of approaching monks (dūratova sambahulānaṃ bhikkhūnaṃ piṭṭhito piṭṭhito āgacchantaṃ (PTS Ud 76)). The Buddha then describes Bhaddiya as "usually, for the monks, of such an appearance as to be disregarded or despised" (yebhuyyena bhikkhūnaṃ paribhūtarūpaṃ (PTS Ud 76)). Again, Malalasekera, Dictionary of Pāli Proper Names, s.v. 'Ambātakavana' (Vol. 1, p. 162), informs us that the Elder Lakuṇṭaka Bhaddiya "lived there, in solitude, wrapt in meditation", supporting this with a reference to Theragāthā 7.2 (PTS Th 49)).
On the theme of the 'oneness' or 'aloneness' of the Arahant, we might also cite the following stanza from Suttanipāta 5, §1142 (PTS Sn 220). (Note that the commentary analyses tamanudāsino into tamonudo āsino (PTS Sn-a ii.604).)
The Cūḷaniddesa also provides a commentary to this same stanza (Myanmar Nidd II, 210-213), wherein, with reference to the word eko, 'one' or 'alone', in the phrase, "eko tamonudāsīno", it says:
'One' (or 'alone'): the Blessed One, by being classified as one who has taken up the ascetic life, is one; by the meaning of being without companions, is one; by the meaning of having renounced craving, is one; absolutely [ekanta] free of passion, is one; absolutely free of ill will, is one; absolutely free of delusion, is one; absolutely without defilements, is one; having gone [gato] by the one-way path (or the one-goal path) [eka-ayana-magga], is one; having fully and perfectly awakened in the one ultimate right and perfect awakening, is one.
Here, in this passage, we find an echo of both of the senses that I have proposed, hypothetically, for ekāra read as 'one-going': namely, both 'going alone' and 'going one way'. Finally, we might consider also this passage from Dhammapada (Ch. 23, §305, PTS Dhp 43):
Even so, in this present context, I have ventured a slightly different reading. Lābha means 'receiving, getting, acquisition, gain' (from the verb labhati, 'to get, receive, obtain, acquire'). Laddha (past participle of labhati) is 'having obtained, taken, received', and thus suladdha is 'well-received, well-gained'. If we took both occurrences of te as instrumental, 'by you', we might arrive at the alternative rendering that I have proposed. More colloquially expressed, the sense would be: "You got it, householder, you got it well, householder!" This would provide a neat sense, given the context of the 'riddle' that Kāmabhū has posed, and Citta's fairly thorough solution of it.