Mazda BT-50 Diesel Problems

It could be the diesel particulate filter alerting you that it's doing its thing. DPFs regularly go through a regeneration process, and most do it while you're driving along without any real impact on the performance of the car.

There are a number of heavy trucks running dual-fuel systems with a blend of diesel and natural gas, on some the gas is compressed (CNG) and on others it's liquefied (LNG). There are also other heavy truck systems that use diesel and LPG. We have reported on all of them over the past couple of years. In the case of light commercial vehicles the systems employed use diesel and LPG, substituting LPG for diesel, and as you say it needs to be very carefully controlled. The more LPG you use the more power you will get, but if it's not well controlled you run the risk of damaging the engine and that's very costly.

The fuel consumption figures you have supplied don't seem to be too far off what Mazda claims it should do. Mazda claims an urban fuel consumption of 11.76 L/100 km, which would appear to be in line with your 11.0 L/100 km, and a combined figure of 8.9 L/100 km, which would seem to be in line with your 8.8 L/100 km. The type of driving has an enormous impact on fuel consumption and I suspect that's the main factor in what you are seeing. If you want to have the vehicle checked take it to a diesel mechanic.

I wouldn't bother contacting Mazda, the car is seven years old and there's no proof that anything was amiss with it from new.

A lot of the new generation of common-rail diesels rattle cold, no matter the brand. They all use the same fuel-injectors, which appear to be the cause of the problem, and there doesn't appear there's much that can be done about it.

It's too early for a reliability read on classy utes such as the Ford Ranger/Mazda BT50 and VW Amarok, which with their lusty turbo diesels are great for heavy work.

It seems to be a problem with modern common-rail diesels and is related to the injectors. Replacing the injectors is the favoured fix.

I would urge caution. These systems work by substituting a percentage of the diesel fuel with LPG and do deliver more power or better fuel economy depending on how you drive the car. The general idea is that you don't have to depress the throttle as far to get the same performance and you can then realize some fuel consumption savings, but I have had quite a number of reports of serious engine meltdowns because the driver simply couldn't resist the temptation to keep the foot down on the throttle. My concern is also that there isn't the same experience with these systems as there is with dual-fuel systems on petrol engines, so they're more exposed to problems. Before you do it talk to other owners about their experience with the systems.

It's OK but the Ford Ranger and Mazda BT-50 are better. The Mazda gets The Tick based on lower prices for better value.

Mazda’s advice is probably on the money. Worn injectors are a common cause of a rattle on cold starts on common-rail diesel engines like you describe.