I have tried Dave's Soundpack, and indeed it is better. But there is a huge amount of reverb, it sounds like the car is placed inside a huge metallic can or something.

No, it is not the transmission whine. That is OK. What I don't like is the total lack of personality. In previous versions the LX6 sounded so great I could just stand still and rev the engine for fun.

Quote from geeman1 :

The vacuum sound you are referring, is the transmission whine. Altough I am not sure if it is 100% correct, it's generated on the fly and real life has it too.

It was a long time ago since I played LFS, 4-5months or so, but now I wanted to have some fun and installed the latest version.
But to my HUGE disappointment all cars now sound like some kind of vacuum cleaners! I really loved the raw clean sound of the LX6 and Formula V8 for example, but now the experience is totally ruined. :/
There is also a lot of "room echo/feedback", setting "echo" to 0, does not remove this.
It sounds just as bad as any other "racing game" out there, with some kind of pitch variated sampled sound, with a blanked on it to attenuate high frequencies.

Is there any way to get the "old" sound back without downgrading to an earlier version?