The Grihya Sutras, Part 1 (SBE29), by Hermann Oldenberg, , at sacred-texts.com
1 1. When going to mount a chariot he should touch the wheels with his two hands separately with (the words), 'I touch thy two fore-feet. Thy two wheels are the Brihat and the Rathantara (Sâmans).'
2 2. 'Thy axle is the Vâmadevya'with (these words he touches) the two (naves) in which the axle rests.
3. He should mount (the chariot) with the right foot first, with (the words), 'With Vâyu's strength I mount thee, with Indra's power and sovereignty.'
4. He should touch the reins, or if the horses have no reins, (he should touch) the horses with a staff, with (the words), 'With Brahman's splendour I seize you. With truth I seize you.'
5. When (the horses) put themselves in motion, he should murmur, 'Go forward to thousandfold successful vigour, divine chariot, carry us forward!'(and the verse), 'Free, strong be thy limbs!' (Rig-veda VI, 47, 26.)
6 6. With this (verse he should touch also) other articles of wood.
7. 'May the two oxen be strong, the axle firm' (Rig-veda III, 53, i7)with (this verse) he should touch (each) part of the chariot (alluded to in that verse).
8. With (the verse), 'The earth, the good protectress, the unattained heaven' (Rig-veda X, 63, 10) (he should ascend) a ship.
9. With a new chariot he should drive round a widely known tree or round a pool that does not dry up, with his right side turned towards it, and then should fetch branches which bear fruits,
10. Or something else that belongs to the household.
11. (He then) should drive (in that chariot) to an assembly.
12. Having murmured, while looking at the sun, (the verse), 'Make our renown highest' (Rig-veda IV, 31, 15), he should descend.
13. 'To the bull among my equals' (Rig-veda X, 166, 1)(this verse he should murmur) while approaching (that assembly?).
14. 'May we be called to-day Indra's best friends' (Rig-veda I, 167, 10)when the sun is setting.
15. 'Thus I address you, O daughters of heaven, while you arise' (Rig-veda IV, 51, 11)when day appears.
209:1 6, 1. 'He should touch at the same time the right wheel with his right hand, the left wheel with his left hand.' Nârâyana.
210:2 On the Vedic form of the chariot and of the wheels, comp. Zimmer, Altindisches Leben, p. 247.
210:6 According to Nârâyana this Sûtra would refer only to other vehicles of wood, which he is directed to touch with that Rik when going to mount them. Perhaps the commentator is right; the wording of the Rik is well in keeping with his explanation.