I have hyundai accent 2000 1.3 GLS with 85000km past.
I have two problems.
-First is that gasoline consumption is 12L on 100km city drive.
Engine is working so quiet,I changed recommended gasoline filter, air filter, spark plug and engine oil. Why is gasoline consumption high?
-Second is that I have problem with transmission.
Sometimes everything is ok I drive car for 50km and there is no problem(I can gear so easy), but sometimes when I put from first gear to second gear transmission scratch, then also scratch when I put from second gear to third gear, or four gear to third scratch(all the time it's hard to gear-like something is stuck), I stop(engine is working) and drive again but problem with transmission is still there. Only when I stop and turn off the engine, then after 5 min. turn on again transmission is ok there is no problem. There is no importance if is machine cold or hot, or transmission is slow or fast, or I change gear on 2000rpm or 3000 rpm.
I changed recommended transmission oil but problem is still there, why?

 

Are the poor mileage and tranny shifting problems both recent phenomenons, or have they persisted for some time?

 

I bought the car and see that have a problem with transmission and gasoline consumption. After 1 day I see that have problem with transmission, after 200 km I see that gasoline consumption is high.

 

I think both problems are related to a worn out clutch. It doesn't take much slippage to kill the mileage, especially during acceleration or when driving up grades. When circumstances require a fair amount of shifting, the clutch starts to overheat and then has trouble disengaging. I would have a mechanic check out the clutch.