Instructions
Open your Web browser and navigate to roblox.com, then enter your username and password to log in to your account.
Run "Roblox Studios" to enter the game's creation mode.
Click to open the drop-down menu in the upper right corner of the screen and select "Models," which provides you with access to all of the game's free models. Drag bricks from the menu into the game field. A car requires four wheel-like bricks, such as cylinders or spheres, connected to a central chassis with a hinge. Insert hinges by clicking the "Hinge" button in the bar along the top of the screen.
Enter "vehicle seat" in the search box within the Models window in the upper right corner of the screen. Give your car a vehicle seat by clicking on the vehicle seat brick in the resulting search and then dragging it onto the vehicle.
Click the vehicle seat to access its variables, which appear in the lower right corner of the screen. Look in the Properties window in the lower right corner of the screen to determine the front orientation of the vehicle seat. In the Properties box, select "Surface," "Front Surface" and then "Hinge" to make a yellow peg appear on the vehicle seat. Click the vehicle seat and hold the mouse button down to rotate the seat so it is oriented in a position that suits you.
Modify the max speed variable by clicking the box next to Maximum Speed and typing in a new speed. Higher numbers result in a higher max speed. The minimum speed is 0, however, if 0 is the max speed the vehicle won't be able to move. The highest speed is 100, but a speed of 100 is very hard to control. You can also alter other variables, such as turn speed and torque. Experiment with different variables to build a car that handles the way you like.
Select all the bricks that will compose the vehicle. Deselect all other objects and click and drag the mouse to create a box in the "Roblox" game creation screen around the vehicle. Make sure the entire vehicle and only the vehicle is contained within the borders of the box. Right-click the vehicle and select "Group all" to combine all the car's pieces.
Click "Save" and then run "Roblox" in game mode to access the vehicle. Approach the vehicle and click on it to enter the vehicle seat. The controls for a vehicle are identical to the controls for normal player movement.