How to change steering sensitivity?

Using a keyboard I find it hard to steer. When I steer the sensitivity is VERY high. Is there any way to turn it down?

 

I would highly recommend getting a PC gamepad. You can pick them up as cheap as £10 or about $15 for those in the US. I got a Thrustmaster GPX for £20. I know that doesn't answer your question but this is a simulator design with with axes in mind and not binary (buttons basically)

 

As Chainsaw said, you really should get some kind of controller.

To more directly answer your question: It's not a matter of sensitivity. There is no way to make the keyboard commands anything but ON/OFF. That means, when you steer right, it yanks the wheel ALL the way right. When you step on the gas, you floor it. No in-between. A controller or wheel will allow you the control you seek.