Mazda 6 2006 Problems

If the engine is damaged as you state the best option is probably to buy a sound used engine from a wrecker. Rebuilding the engine could cost $5000, a good used engine should be bought for less than $2000.

When doing your research you need to dig deeper and find out the claimed fuel consumption for city and country driving. The Mazda 3 manual is claimed to return on average 7.9 L/100 km, but when you look at the claims for city and country you find that it does 10.8 L/100 km and 6.2 L/100 km respectively, which lines up reasonably well with your experience remembering that the claimed figures are not real life ones like your own are.

It's frustrating that discs should need replacing at such low kays, but it's not that unusual today. You got 65,000 km out of the second set of discs, which is par for the course. It is something I think carmakers should be looking at and developing new materials or whatever to extend the life of the brakes.