Learn Swedish: Min kollega hyrde bilen och körde hem. - My colleague rented the car and drove home.

Both of these verbs belong to Group 2a. For this group, you form the past tense (preteritum) by taking the stem of the verb (like hyr- from att hyra or kör- from att köra) and simply adding the suffix -de.

Is it tricky to find the stem for verbs like hyra and köra?

It can be! For many verbs, the present tense ends in -ar or -er, and you remove the -r to find the stem. But for verbs whose stems already end in an -r (like hyr- and kör-), they don't get an extra -r in the present tense (they are just hyr and kör). However, in the past tense, they follow the rule perfectly: just add -de to get hyrde and körde.

Why does the sentence use hem instead of hemma?

In Swedish, there's a strict difference between moving towards a place and already being located there. Hem means "homeward" or "to home" (direction), which fits here because the colleague is driving. If the colleague was already parked at home, you would use the location word, hemma.

Why isn't there a pronoun after och, like ?