I enjoyed LX6 / mouse a lot until I bought a wheel.
Some more tips:
1) LX6 / mouse will be driveable if you set the "button control rate" lower than with other cars. Try the lower end values, maybe around 3-4.
This will artificially smooth your inputs (throttle / brake) and the car will become more stable. It should also reduce spinning tendency. Warning! Braking a bit earlier is necessary because full braking power will no more be available when you press the button.
2) Brake balance is a setting you should play with - less front bias mousing that using the wheel
3) Now the difficult part: To be fast with LX6 you will have to tap the buttons, especially throttle. Tapping frequency required is lower if the "button control rate" is low. This will be necessary to keep some gas in the corners, accelerate early enough, and brake late. I recommend (if not done already) that you use KB buttons for throttle / brake and keep the mouse for steering and gear changes, that is slightly more stable and ergonomics.
4) When you reach 1-2s off WR, get a wheel or get in touch with Palluka because I can no more help