This particular Rigvedic verse mentions the gods Soma and Pushan riding together on a chariot:
1 SOMA and Pūṣan, Parents of all riches, Parents of earth and Parents of high heaven, You Twain, brought forth as the whole world's protectors, the Gods have made centre of life eternal.
2 At birth of these two Gods all Gods are joyful: they have caused darkness, which we hate, to vanish. With these, with Soma and with Pūṣan, India generates ripe warm milk in the raw milch-cows.
3 Soma and Pūṣan, urge your chariot hither, the seven-wheeled car that measures out the region, That stirs not all, that moves to every quarter, five-reined and harnessed by the thought, ye Mighty.
4 One in the heaven on high hath made his dwelling, on earth and in the firmament the other. May they disclose to us great store of treasure, much-longed for, rich in food, source of enjoyment.
5 One of you Twain is Parent of all creatures, the other journeys onward all-beholding. Soma and Pūṣan, aid my thought with favour: with you may we o’ercome in all encounters.
6 May Pūṣan stir our thought, the all-impelling, may Soma Lord of riches grant us riches. May Aditi the perfect Goddess aid us. Loud may we speak, with heroes, in assembly.
Though the hymn is beautiful and quite interesting in its details my particular question is about the chariot that is mentioned in the highlighted portion. Do any commentaries/other scriptures explain what this seven-wheeled & five-reined chariot could be?