Holden Problems

It depends on the gradient, the idle speed etc., but generally an auto will sit on a slight gradient without rolling back. The idle speed could be a little low. But I wouldn't be concerned about it if it does roll back, it shouldn't have any effect on take-off when you're out driving and have to stop on a hill.

You say it’s new, but not how many kays it’s done. I would wait until it is properly run in before doing anything rash like fitting an aftermarket chip. While they can improve the economy and performance as you say, fitting the chip would void your warranty on the engine and the drivetrain. If you are concerned about the performance first consult your dealer.

Brakes are regarded as consumable items, which are not covered by the warranty. The warranty is there to address defective items in the car. You could argue that a vibration in the brakes must mean there's a defect in them, but the time and effort required to prove that the   vibration was due to a defective part and not use or abuse would be too much to justify doing it.

You don't say by how much it has crept up and whether it's been a gradual increase or a sudden jump, but Holden's claim for town running was 15.0 L/100 km for a 1999 VT V8 and 13.5 L/100 km for a later VX V8. If it's running well and still packs a powerful punch you should look at those items that might affect the tuning of the engine. Replace the spark plugs, the plug leads, the air filter, perhaps clean the throttle body and give it a good run to blow out any carbon build-up.

It could be a question of adjustment of the roof mechanism. I would take it back and have the roof alignment checked and adjusted if needed.

While the carmakers will tell you the transmission is filled for life the old timers in the auto business will tell you otherwise. It’s wise to regularly check the transmission fluid, and change it every 20,000-40,000 km depending on the use. You can leave it longer if it’s being used for normal driving, but if it’s towing it should be changed sooner rather than later. The transmission is working fine and it’s got fresh fluid, so there’s no reason to think there’s a problem on the horizon.

The water pump is usually changed because it’s found to be leaking when the mechanic strips the front cover off the engine to replace the belt. It’s not a regular service item as such, but done because it’s cheaper to do it at the same time the belt is done rather than leave it and have to replace it at a later date. The failure of a water pump is different to that of the belt, it’s usually due to leakage, which doesn’t result in catastrophic internal damage like a belt failure does.

If your Commodore has IRS you’ve got a tyre-eater on your hands and it would be worth talking to a suspension specialist about fitting a kit to the rear suspension to control the toe-in. Tyre specialists also recommend that you regularly rotate your tyres — 10,000 km is the interval they suggest — and have the alignment checked and reset every 20,000 km. Alignment is often neglected, but is an important contributor to tyre life and can be knocked out simply by hitting a kerb or a pothole. After doing that you could fit a Pirelli or a Michelin tyre, which should give you better tyre life.

It could be a faulty shift solenoid or a problem with the throttle position sensor. Take it to an auto trans specialist who should be able to diagnose the problem for you.

It sounds like a fault with an engine sensor or its connections. Check the crank angle sensor.