Use in for (usually) smaller vehicles or crafts that you have to enter and sit in (a car, a taxi, a truck, a helicopter, a canoe, a kayak, a small boat, a carriage, a rickshaw).

In English grammar, the prepositions used with "taxi" depend entirely on whether you are talking about being inside the vehicle or the method of transportation. When you are physically inside the vehicle, you use the preposition "in" (e.g., "I am in a taxi"). This is because a taxi is considered a private, enclosed space that you cannot walk around in. This contrasts with public transport like buses or trains, where you use "on." When referring to the method of travel or how you arrived somewhere, you use the preposition "by" (e.g., "I came here by taxi"). You might also use "into" or "out of" when describing the action of entering or exiting the vehicle (e.g., "She jumped into a taxi" or "He got out of the taxi"). In 2026, with the ubiquity of rideshare apps, these rules remain consistent; you are "in an Uber" or "in a Lyft" just as you would be "in a taxi." Using the correct preposition is a key part of sounding natural in English, helping to distinguish between the physical location of the passenger and the general mode of transit being utilized.