I have got the 1984 model of this bike in Feb, 1985 and I have no problems what so ever till date. Good pick-up, mileage. Have problems only for certain spares. after little bit of running around, I get them. I still use it in and around Bangalore during the weekends.
I still see a few well-maintained old ones on the road in Bangalore. Have not checked the mileage during the past few years. The service at the main TVS dealers/service centers is very poor for this vehicle. I prefer to visit the local mechanics who do a much better job, either for just service or sourcing a part.