Car makers will sometimes help out with such problems provided the car has been serviced correctly and not abused throughout its life. I agree that 40,000km is not a reasonable expectation for a modern automatic transmission, so I’d be contacting Hyundai Australia’s customer service division to see if anything can be done. Experience tells me that Hyundai takes its obligations in this area pretty seriously, so you may be offered some help with the cost of repairs.

You could also have the transmission inspected to see what went wrong (your state motoring club is a good place to start for independent inspections like this one) as this information might be very useful if you decide to take the matter further. The ACCC would be the final step in this process, and Australian Consumer Law deals with what is fit for purpose and what is not.

It’s very possible that this is a problem with the brake’s booster system. To give the braking system extra oomph, it uses a vacuum operated booster unit that multiplies the force in your leg. The vacuum comes from the engine’s intake system. If this booster develops a vacuum leak, it can allow excess air into the engine’s intake manifold. This extra air messes up the air-fuel mixture and the engine can start to rev up.

The brake booster is the first place a mechanic will check when presented with this problem.

Taking your car to a Hyundai dealer is a fabulous idea because you might just find that this will turn into a warranty claim where Hyundai foots the bill and not you. Theoretically, your car could still be covered by its original five-year warranty (depending on what date it was sold new) but some Hyundai cars were also covered by extra warranty and extended drivetrain warranties. This is what you need to establish, but a Hyundai dealer will be able to give you the answer.