Hyundai Elantra Problems

The front pads normally do most of the braking and wear out first as a result, but it's not unusual today for the rears to go before the fronts. You could check to make sure the handbrake is releasing properly and not dragging on the discs. I doubt that you have been conned by the dealer, if he was really conning you I'm guessing you would have copped a bill for the fronts as well, and maybe even the disc rotors themselves. If in doubt when in a situation like this ask to see the parts that have replaced. Most dealers are happy to show them to you.

You're right, what the dealer told you is ridiculous. Your description of a car that struggles to reverse up a slight incline suggests a mismatch of engine and gearing, the engine it seems doesn't have enough torque to handle the gearing of the Elantra, and the clutch then becomes the weakest link and the only thing it can do in the circumstances is slip. A slipping clutch is one that wears out quickly.
 

The car obviously doesn't do a lot of kays, having done only 55,000 in eight years; so I'm guessing it sits around idle for much of the time. From the compression figures it could be that the valves are not sealing properly through lack of use. I doubt that you would need a new engine, or a major repair, but if it's now going I would suggest you take the car for an extended drive. If it's not going then you might be faced with taking the head off and checking the valves.

Problems with central locking systems are not unusual, have a locksmith check it. Most locksmiths nowadays have the capability of coding keys for most popular models, and they’re usually much cheaper than the dealers.

You'll find there's also a time requirement on the belt. Even though it's only done 37,000 km it is going on for seven years old, so I would always err on the side of caution and change the belt.

It doesn't sound like a wheel balance issue, but it would be worth having the wheels checked to make sure they are round and haven't been knocked out of alignment. You could spin the tyres on the rims to get the best match of wheel to tyre, and swap tyres from side to side, all to make sure the problem isn't a wheel balance one. Look for a drive shaft problem; it could be wear or damage.

I doubt it is a fuel pressure problem, if it was you would have trouble all the time, not just when the engine is cold. It sounds like the cold enrichment is not working, so have that checked. As for the garage tracking a problem can be a challenge and many a new part is fitted that doesn't do the job. The best thing is to return it to the garage, tell them they haven't fixed the problem and ask them to check it again. If you're not sure they are competent to do the work tell them that you approve of any parts before they fit them.

Your mechanic could apply some anti-rattle grease to the back of the pads that could well stop the rattle.

Hyundai's are generally standing up well to the Australian conditions, and are getting better with each new generation that comes to the market. The clutch went at over 100,000 km, so you have to think that's in the range of being acceptable. The split dash is a little different and I would be trying to get Hyundai to at least contribute to the cost of repairs.

The tyres fitted were indeed an option on the Elantra, they’re a little fatter with a lower profile than the standard tyres. You could fit either, so I would shop around and see which is the cheaper.