Sweeper

The sweeper is a street sweeper.

One spawns in northeast Las Venturas, another one spawns under the highway in south central Los Santos.

More info:
gta.wikia.com/wiki/Sweeper
https://www.grandtheftwiki.com/Sweeper

Quad

The Quad is a four wheel drive ATV. One spawns next to a trailer home to the west of the Verdant Meadows Airfield.

More info:
gta.wikia.com/wiki/Quad
https://www.grandtheftwiki.com/Quad

Mower

The Mower is a lawnmower.

One can be found by a mansion on the Vinewood hills.

More info:
gta.wikia.com/wiki/Mower
https://www.grandtheftwiki.com/Mower

Kart

The Kart is a go kart. The tight turning radius and grip actually makes it hard for me to drive it - it's hard to take gentle sweeping turns.

There are several spawns once you have gone through the DJ Loc/Madd Dogg storylines. These include Madd Dogg's mansion, in the alley next to Zero's RC, and under the bridge near the Stadium in Ganton.

More info:
gta.wikia.com/wiki/Kart
https://www.grandtheftwiki.com/Kart

Combine Harvester

The Combine Harvester is a piece of farm equipment. It's width and rear-wheel steer make it the most difficult vehicle in the game for me to drive.

You can guess what happens if you run over pedestrians with it.

You can find them spawned at Blueberry Acres, the Farm, and Helen Wankstein's farm. They are often locked, so you usually need it to be daytime so they are occupied and then shoot the driver.

More info:
gta.wikia.com/wiki/Combine_Harvester
https://www.grandtheftwiki.com/Combine_Harvester

Forklift

The Forklift is a forklift. It is front-wheel drive and rear-wheel steer. This (and its high center of gravity) make it hard for me to steer.

You can adjust the height of the forks.

One spawns at Ocean Docks in south east Los Santos.

More info:
gta.wikia.com/wiki/Forklift
https://www.grandtheftwiki.com/Forklift

Bandito

The Bandito is a fun, single-seat off-road buggy. It's neat to watch the engine flywheel spin and the suspension components work as you fly over the landscape.

One spawns next to the boardwalk on the west side of San Fierro.

More info:
gta.wikia.com/wiki/Bandito
https://www.grandtheftwiki.com/Bandito