Hi, here are some little ideas/dreams I had in my mind over many years. I think they are pretty easy to implement, and will increase impression of LFS 

EDIT: added things from posts #7, #8.
                
                    
            
- Doppler effect for horn and tyre squeak [✔ thx]
 
- Some kind of blur or another texture for spinning wheels
 
- More mid/high range smooth potholes, asymmetrical waves, ruts on some roadish tracks, to give suspension some work and to thrown off car balance
 
- Tugging ignition cut-off
 
- Kick forward, instead of kick backward when up-shifting sequential gearboxes
 
- More aggressive and within lower revs turbo kick-in
 
- Power steering simulation in some cars - the spring effect is killing me
 
- Less influence of wind from back in cars with wings - I think wings doesn't do same aero job when reversed
 

EDIT: added things from posts #7, #8.
- Various number plate types to choose, not only UK type. For ex. EU, US or another countries where LFS is popular.
 
- Several, like 3 or 4 optional tyre dimensions (xxx/yy R_zz), within same overall wheel size - for personal taste in race/rallycross/rally/rain...?  
 
- Proper trailing arm movement.
 
- Thinner layer of the tread on slick tyres. It will prevent overheating R1's, make R3/4 easier to heat up, reduce the number of laps that can be driven, make wheels lighter(?). Right now you can push on 110% only in the end of tyres' life.
 However this concerns current LFS version 0.6J.
 
- Intake Restriction - as Tristan Cliffe said long time ago, it should keep low/mid revs all torquey and weaken power at higher revs.
 
- #9 Rally barrier tape as layout object
 
