The drive around servers are a sort of novelty, but not much fun at all. There are better games to do those sort of things; LFS just doesn't have the features necessary to make that gameplay fun.
It's almost the perfect example of "just driving around" fastidiousness. Especially when the players on the server do only that, sort of like they're playing SecondLife or something. You play games like LFS to do what you can't do in real life, not to have some netcop get on your case..
Adding just open city streets would be a major improvement, but given LFS' priorities and development resources, it's not likely to happen soon.
I'd say ballast would be the one smallest, most effective improvement... it'd fix the classes, which needs only a well organised server setup to make for consistently great racing, like STCC does.
Considering how busy the devs are, I think a more complete LFSTweak would take care of the lack of new cars.. it's really the best solution for the situation LFS is in.
If we could change all the old Tweak parameters or more, and the suspension types, we could have some great "new" car classes to race.
LFS is about racing, and it does it great.. Scavier know it and are on the right track.