Run-flat tyres were the car companies’ way of making more luggage space and cutting cost from each car. But they had their problems including the noise you’ve mentioned as well as a lack of ride quality. Although, to be fair, the latter has improved massively in recent years with new generation run-flats hitting the market.

A good tyre specialist should be able to advise you on which run-flats are the current favourites in terms of noise and ride, as well as grip and price. But it’s worth mentioning that tyre manufacturers are constantly trying to outdo each other, so the improvements keep coming. The best tyre today might not be the best one in a few months’ time.

The concept of a larger (wider) tyre on the rear of your car is to do with grip and handling. Messing about with this relationship could lead to a less athletic car and there are physical limits on what tyre can be fitted to what rim.

You could make the switch to a non-run-flat tyre and buy a tyre repair kit to keep in the boot. In fact, many owners of earlier cars with run-flat tyres have done just that. You still stand to pick up a little ride comfort by doing so, but nowhere near as much of an improvement as you would have, say, a decade ago.

It’s definitely true that the march of new-car technology is making big changes to the cars we’re being offered almost on a monthly basis. So, if your current car is just three years old, it might be worth holding on to it and waiting for the next big thing to arrive in showrooms. Certainly, by trading-in at just three years, you’ll pretty much max out the depreciation you’ll suffer in financial terms.

But by waiting, you might find that you can buy an electric vehicle and be able to tap into newer and better infrastructure that will be in place in another few years, rather than put up with the relatively sparse charging-station network currently in this country.

At the moment, a hybrid or plug-in hybrid is a pretty good way to go, provided you use the vehicle mostly in an urban setting, rather than long-distance freeway journeys where the hybrid tech is less advantageous. A hybrid is not exactly future-proof, but it’s a good next step for a lot of Australian car-owners.

As for what brand is best, the tech is getting better and better as time goes by, so it’s likely to be build date rather than brand that will determine the efficiency of the vehicle in question. That said, car owners can’t hold off forever when it comes to upgrading, so for the moment, a hybrid or plug-in hybrid is a logical next car. We’re particularly impressed by the current-model Toyota Camry which is good value to buy, a classy driving experience and offers hybrid fuel efficiency in the right environment. Such cars will be a lot of Australian families’ first hybrid, and rightly so.

Did you replace the coolant tank because the vehicle was losing coolant in the first place? If so, there’s a chance that even though the coolant tank is brand new, there could be a leak from somewhere else in the system (that’s allowing the system to lose pressure, as you’ve identified). Possibilities include the radiator itself or even a head gasket, not to mention any one of a number of plastic fittings that control the flow of coolant to the engine and the car’s heating system. But don’t rule out the simple stuff, either; even the humble radiator cap or loose hose-clamp can allow pressure to leak from a cooling system.

The problem with a lot of imported cars is that they tend to use lots of plastic components in their plumbing systems. As they age (and at 16 years old, your car is hardly in the first flush of youth) these fittings and couples become brittle and can begin to leak or even fall apart altogether. In colder climates, these plastic bits and pieces don’t present the same problems to the same degree, but here in Australia, our hot-climate heat-cycles are not appreciated by some makes and models. Combine that with a modern, pressurised cooling system, and you have yourself a problem.