Looking on the internet deeply has found these results:

We went there in a minibus. is the most popular phrase on the web.

We went there on a minibus. 13 results on the web	We went there in a minibus. 14 results on the web More popular!
Some examples and use cases from the internet:	Some examples and use cases from the internet:
Then I got knocked over by a minibus. First we went here, and then we went there... She went into this shop, that shop, took a bus, a minibus. I move to the left lane to overtake a minibus. Well, that would make Christmas very pricey, plus even a trip to Chessington World of Adventures, we'd have to hire a minibus. Then I got knocked over by a minibus. Remember we went there together once. Doris must have found out we went there and discovered the truth.	Well, that would make Christmas very pricey, plus even a trip to Chessington World of Adventures, we'd have to hire a minibus. If you see a mad professor in a minibus, just smile! I move to the left lane to overtake a minibus. Say, do you and your friends shack up in a minibus, or aren't things that cozy? Then I got knocked over by a minibus. Then I got knocked over by a minibus. I was traveling around in a minibus with a guy selling clothes. She went into this shop, that shop, took a bus, a minibus.

We went there on a minibus.

13 results on the web

We went there in a minibus.

14 results on the web

More popular!

Then I got knocked over by a minibus.
First we went here, and then we went there...
She went into this shop, that shop, took a bus, a minibus.
I move to the left lane to overtake a minibus.
Well, that would make Christmas very pricey, plus even a trip to Chessington World of Adventures, we'd have to hire a minibus.
Then I got knocked over by a minibus.
Remember we went there together once.
Doris must have found out we went there and discovered the truth.

Well, that would make Christmas very pricey, plus even a trip to Chessington World of Adventures, we'd have to hire a minibus.
If you see a mad professor in a minibus, just smile!
I move to the left lane to overtake a minibus.
Say, do you and your friends shack up in a minibus, or aren't things that cozy?
Then I got knocked over by a minibus.
Then I got knocked over by a minibus.
I was traveling around in a minibus with a guy selling clothes.
She went into this shop, that shop, took a bus, a minibus.