Case Study – Econcertive (Terraclean)

Subject Area: Transport (engine treatment)

Sector: Business Services

€concertive has been running the same diesel vehicle for almost six years, and its fuel performance has always been monitored. Not surprisingly, this had gradually deteriorated with time and mileage. The drop in performance will be due to a combination of engine wear and carbon build-up.

The ‘normal’ way to address this would be to strip down and de-coke the engine and the fuel system, including the fuel injectors. This is a labour intensive (and therefore expensive) process, and very hard to justify for an engine which was otherwise running perfectly.

Terraclean offers an alternative decarbonising process which is carried out without dismantling the engine and at a much lower cost. We decided to put it to the test.

The Test Vehicle

The car is a Volkswagen Passat Estate with a 1.9 litre turbo diesel engine. It was 5 years old when purchased, with 96,000 miles on the clock. At that time it delivered an average of 49 miles per gallon (MPG).

As an 11 year old car, with 220,000 miles on the clock, its average performance had reduced to 45.5 MPG with a similar journey mix. Other than oil, filter and timing belt changes, the engine had never been touched during the intervening period.

The Process

Terraclean is a mobile service and the company comes to you to carry out the work. It is basically a chemical process which involves bypassing the fuel system for a period and running the engine from the Terraclean fuel and decarbonising chemical mix. The whole process took around an hour.

For the purposes of this case study, the vehicle was also subjected to an emissions test prior to the visit and a further test about a month afterwards, once the full effectiveness of the Terraclean process had bedded down.

The Results

There was an immediate and marked improvement in responsiveness as soon as the car was back on the road. The change in fuel performance was more gradual and took several tankfuls of diesel to take full effect. The new fuel performance averaged 48 mpg, representing a 6% improvement in overall fuel economy.

The improvement was initially more noticeable on longer journeys (the car has an on-board computer which monitors MPG continuously), but over time it became equally apparent on shorter journeys.

Prior to the Terraclean process, the engine exhaust smoke emissions were measured at 2.7 m-1. By way of comparison, the NCT maximum limit for a pre-2008 diesel is 3.0 m-1, so it just passed the legal requirement.

The follow-up test showed smoke emissions reduced to a remarkable 0.8 m-1. This is a 70% reduction and brought the car well below even the modern NCT diesel smoke emissions standard of 1.5 m-1.


The Terraclean service has resulted in significant improvements in the car’s fuel efficiency, smoke emissions and responsiveness to the accelerator, with no down-sides apparent. The process itself was fast and convenient, with no need to take the car in to a service centre.

In terms of cost-effectiveness, at the current low fuel prices (January 2016) and an annual mileage of 24,000, the payback time for the Terraclean service cost for that engine size will be a little under 1 year. The recommended interval between Terraclean services is 12 – 18 months, so at the very worst, it covers its own costs.

Terraclean also produce a fuel additive which should help to prolong the effectiveness of the process, so the expectation is that it will provide a comfortable net financial saving, while significantly reducing the overall environmental impact of the car. When fuel prices start to increase again (as they inevitably will) the financial savings will become more pronounced.

For more information about Terraclean visit their website