Expert answer

Hi Marnie,

It could well be that the wrong type of battery was used, so perhaps take a look at that, but there can be many other reasons causing the stop-start system to give an error. Really, it needs to be plugged into a diagnostic computer to get to the bottom of the problem. A good mechanic should be able to do that for you.

Expert answer

Hi John,

You've not mentioned which gearbox specifically, so we'll assume you mean the DSG automatic. These can develop faults with the 'mechatronic' unit that controls gear shifting etc. If that has to be replaced then it's expensive, though sometimes just changing the transmission fluid helps.

That needs to be done regularly in DSG units using the 'wet-clutch' setup. Those with the dry-clutch system don't need such maintenance.

If you've thinking about buying a car using a DSG transmission, then make sure you take it for a decent test drive through the full speed range up to motorway speeds and monitor the gear changing for judders or other issues. If possible, spend some time in stop-start traffic as well as that can cause the clutch packs and mechatronic unit to overheat if they are weak and you'll soon notice if something isn't right.

Saying all this, the DSG transmissions aren't necessarily bad designs, you just need to ensure the one you're buying is still operating properly.

Expert answer

Hi Gerry,

We do try to observe and mention real-world fuel consumption in our reviews, when possible, though the launch routes aren’t always very representative of the real world and sometimes are too short to get a proper feel for such things.

There’s no doubt that a car’s economy varies massively depending on where and how it is being driven, though I am a little surprised your Octavia hits nine litres per 100km at times. That sounds a little high. Maybe mention it to the garage next time you get the car serviced so they can look for any issues.

(The Skoda Octavia review can be found here)

Expert answer

Hi Catherine,

Stop-start systems can be tempermental. We get so many queries about them that we decided to write a feature explaining the potential issues - Why won't my car's stop-start system work?

Nonetheless, issues with it are regularly caused by weak batteries. Saying that, I wouldn't expect your car to start properly in the morning if there was a big battery problem, so I don't think the boot opening problem is linked to the battery. The Fiat 500 has a known issue where the wiring near the tailgate hinge can become damaged or broken - I suspect that's where your problem lies.

A decent mechanic should be able to quickly fix that for you.

Expert answer

Hi Teresa,

We used to get so many queries on this subject that we published a feature called Why won't my car's stop-start system work?

If you read that you'll discover that the systems are highly sensitive to battery charge and load, even when working perfectly. Could it be that you often have high-load items switched on? Things like heated seats, air conditioning, rear window demister, that sort of thing.

Now, in a DSG-equipped automatic car, you shouldn't need to put the car into neutral to get the stop-start system to work - that's only on manual cars. You can leave it in D (drive). What does affect it, however, is how firmly you are holding your foot on the brake pedal when at a standstill. Sometimes it's necessary to give the brake pedal a firm push before the engine will cut out.

Other things to watch out for: if you move the steering wheel, it is likely to cause the engine to restart. And if you're in the Sport driving mode or you've selected the Sport gearbox setting, then stop-start might not work either.

If none of the above changes your experience, I suggest getting a mechanic to come out in the car with you to check it over and observe how you drive, and then let them do the same.

Best of luck with it - come back to us and let us know how you get on.

Expert answer

Hi Justina,

Start-stop issues are common with a lot of cars and we get many queries about it. If your car is not being used much right now, then the battery may not be in great condition and that's a leading reason for stop-start problems. It could be something else of course. Your car should still be under warranty if you want to talk to your Hyundai dealer about it.

In the meantime, read Why won't my car's stop-start system work? on the subject.

Expert answer

Hi Ricky-Lee Morgan,

In the vast majority of cases this is down to either a battery that is not in perfect health or a dodgy sensor. See our feature Why won't my car's stop-start system work? and if that doesn't help then you will need to get the car plugged into a diagnostic computer by a mechanic.

Expert answer

Hi Ann,

We'd suspect the battery or alternator aren't performing at their best. Stop-start issues are very commonplace, across all cars. So much so that we've written a feature for drivers on the subject: Why won't my car's stop-start system work?

Expert answer

Hi Tanya,

It sounds to us like the alternator may have been struggling to produce enough electrical power and that perhaps your battery could do with replacement. If the problem has not reoccurred then it's nothing to worry about, but no harm getting your battery checked before winter sets in.

Expert answer

Hi Brian,

We get so many queries about stop-start systems (in all makes and models) that we wrote a feature about it: Why won't my car's stop-start system work?

However, in your case, perhaps there's something up with the alternator that prevents it from charging up the battery fully. 

It may be worth getting an auto-electrician to check it out.