A four-speed automatic transmission is also available as an option.

Literal

Option [as-として] 4-speed automatic-transmission [also-も] choose-able.

オプション 'option' and 4速自動変速機 '4-speed automatic transmission' (速 'speed' + 自動 'automatic' + 変速機 'transmission') mix loanwords with sinitic technical compounds. ~として 'as / in the capacity of' marks the role. 選べる is the potential of 選ぶ 'to choose.' A clean, factual automotive specification sentence.