Carrera Track: Advice on tuning other car bands?

I am having so much fun with my Carrera Digital - but I really want to try out some other analog cars by different manufactures.

I could use some advice on how to set up these other brands for carrera track. I have a small analog test track. I have tried a scalextric and a slot.it car.

The scalextric GT40 seems to run pretty good out of the box.

I had read some many compliments on the slot.it brand, I bought a slot.it Nissan R390.
A beautiful looking car - but I am having a couple problems:
Brushes not having good contact with carrera track.
Car seems to de-rail easier than the scalextric.
Maybe something with the guide? Tips appretiated.

I plan to set up my larger carrera "digital track" this weekend - removing the digital components and adding the automatic lane crossing and operating in analog mode. I'll be able to compare my carrera digital car running in analog mode to the scalextric and slot.it.

I'll take any advice that will help improve the performance of other brand cars on carrera track.

You are welcome to point me towards posts that already discuss this. I have tried "searching" without much luck.

Thanks!

Jon

Jon