The real cost of roof-mounted extra lights

The simulation shows how extra lights increase the pressure in the critical area where they are mounted. This leads to reduced forward suction at the roof transition area, which results in increased fuel consumption

Even though European trucks might seem fairly brick-shaped, the OEMs put vast resources towards streamlining the vehicles as much as possible. The rules regarding maximum length however necessitates a design that uses a rather flat front – since profitability increases with a longer cargo area. That is why a longer, more aerodynamic, nose is not currently used, since a longer tractor would result in a shorter load carrier to stay within the maximum allowed vehicle length.

As the truck travels along, air molecules will stagnate against the front of it which builds up a high air pressure at the surface. This pressure pushes the truck against the direction of travel and is the biggest contributor to total air drag. This effect is however counteracted somewhat through a powerful low pressure that develops at the front corners of the truck – which sucks the vehicle forward. To achieve as low aerodynamic drag as possible, a lot of development resource is therefore usually allocated to trying to maximize this forward suction.

What most people however don’t think about is how significant the negative impact from common add-ons is on the truck’s aerodynamic performance. Roof-mounted extra lights are usually mounted in a way which severely impacts the forward suction that normally is created at the transition from the truck’s front to its roof. This leads to a significant increase in drag, and thereby fuel consumption, that is a lot bigger than the direct contribution from the lights themselves.

To illustrate this effect, Rumblestrip has simulated the aerodynamics of a European-style semi-trailer truck. Air drag is compared between a standard “clean” truck and one with an extra lights ramp consisting of six lamps which are mounted on a standard roof rail. The air is coming towards the truck slightly from the left at an angle of five degrees to mimic realistic wind conditions.

It turns out that the extra lights increase the aerodynamic drag by more than 6 %, which corresponds to an increase in fuel consumption of 1 L/100 km for long-haul trucks. With a typical yearly driving distance of 150 000 km, this means that the truck consumes as much as 1500 litres extra each year only because of the extra lights!

The real cost for mounting extra lights therefore greatly exceeds their purchase price over the course of the truck’s life span. Each year, they may cost as much as €2.000  in increased fuel costs (about as much as the purchase price). The CO2-emissions increase by more than four tonnes each year – more than double the emissions of an average car.

Of course, some trucks really do need to add extra lights. But it would certainly be good if one at least contemplates whether the benefit from them is worth the significant extra cost that they incur. Alternatively, one should try to mount the lights in other positions of the truck that are not as aerodynamically sensitive as the normal position.

It is a lot worse with aerodynamic nightmares such as the Michelin Man figures or large “billboards” that are often found mounted on trucks, and whose practical benefit could be questioned. Would it be considered reasonable to drive around with these if their true cost through increased fuel consumption was fully known?

Instead of wasting money on add-ons that could cost 2 000 Euros per year, the alternative could be to buy the automatic roof deflector Ecosense Trailer Assist which instead could save as much money and CO2-emissions each year. The system makes sure that the truck’s roof air deflector is always optimally positioned after each trailer or load carrier change. It is an investment that pays for itself quickly and then delivers pure profit from the achieved fuel savings. Great both for the hauler and for the environment!

Up to 2 L / 100 km fuel saving with Ecosense Trailer Assist for Trönninge Åkeri

For Trönninge Åkeri from Halmstad, it is extremely important to keep fuel consumption down as much as possible. It is not possible to charge more from the customers because the trucks uses more fuel. Every percentage of fuel that can be saved gives a direct effect on the financial result.

When Mattias Creutz, owner of the haulage company, heard about the automatic roof air deflector Ecosense Trailer Assist, it was interesting for him to try the system on one of his trucks, a Volvo Globetrotter XL. The result has been excellent – a fuel saving of up to 2 L / 100 km, which corresponds to just under 6%, compared to the original solution. It’s not that weird; the truck changes trailers every day and the height often varies greatly.

With an average mileage of 800-900 kilometers per day, the savings can be almost 20 liters a day. Seen over a whole year, there will be large sums. ”I would rather go to the Canary Islands for that money than to donate it to the oil companies,” says Mattias.

“Next time we buy a new truck there is nothing to discuss, the Ecosense system should be there! The system cost a little bit, but I save that cost within a year. There are not many things with a return of investment of just one year in this industry. After a year, the fuel savings that the system delivers will be pure profit. I do everything I can to save fuel, ”continues Mattias.

For both small and large hauliers, it is becoming increasingly important to save fuel, for the sake of the wallet and the environment. Trönninge Åkeri is another in the line of hauliers that have found the benefit with Ecosense Trailer Assist, the system that ensures that the roof spoiler is always set in an optimal position regardless of load or trailer.

For more information:

Milad Pouyanmehr, Rumblestrip, +46 76 760 74 03,

Mattias Creutz, Trönninge Åkeri, +46 70 976 16 52,

Wiréns Åkeri saves 25,000 SEK per year with Ecosense Trailer Assist

Wiréns Åkeri is a transport company that was founded as early as 1946. The company is located in Kristinehamn near Vänern in Sweden and transports components for Volvo Construction Equipment, as well as long distance transport for DHL. Wiréns have a big focus on environmentally adapted transports and works actively to reduce the environmental impact of its transport. As a result, they chose to try Ecosense Trailer Assist on one of their trucks, a Volvo FH Globetrotter with medium sized roof air deflector. 

In the original version, The Volvo roof air deflector is almost impossible to adjust on the roads. It would require two people who climb high, use tools to unscrew the braces, and then adjust the height of the heavy system simultaneously on both sides. In practice, such interventions are only done in the workshop.

With Wiréns driving trailers that are 4.5 meters high for Volvo CE and then switching to significantly lower trailers for DHL, the penalty for not adjusting the angle of the roof air deflector can be great. Ecosense Trailer Assist is perfect for such situations; at each trailer change, the roof air deflector optimally adjusts to the trailer you are driving with at the time. A maneuver that would have been both very time consuming and risky to try with the original system.

The first figures from the test show promising results. Adjusted for seasonal variations, fuel savings have been a little over 1 L / 100 km during the first few months. With a typical mileage of 180 000 kilometers per year, the savings will be about 25,000 SEK per year for the truck with Ecosense Trailer Assist. 

Kalle Ekeberg, vehicle manager at Wiréns, says: “It is fun to see that the system works well and that we save fuel. Every penny is important – if there are solutions to save fuel, you have to invest in it! Our drivers are curious and usually look out the window as the roof air deflector sets in during the trailer changes. Yesterday we installed Ecosense Trailer Assist on another truck and it will be interesting to see the savings there as well.”

For more information:

Milad Pouyanmehr, Rumblestrip, +46 76 760 74 03,

Kalle Ekeberg, Wiréns Åkeri, +46 550 387 93,

Three percent fuel savings for Wiklund Transport

Scania Next Generation lastbilar med Ecosense Trailer Assist under installation

Magnus Wiklund, owner of Wiklund Transport in Larsmo in Finland, has driven Scania trucks during many years. Since he ordered three New Generation Scania, he has made sure to tell his drivers to adjust the roof air deflector every time they are changing load carrier, in order to minimize the fuel consumption.

Thanks to the new Scania trucks having an adjustable roof deflector using a manually operated crank, it has not been too difficult for the drivers to follow Magnus’s wish. Setting the spoiler position has however mostly been done by feel since it takes too much time and effort to do the detailed measurements necessary to set it according to Scania’s handbook.

Magnus Wiklund therefore saw the potential in a fully automatic system that would always set the roof air deflector in its optimum position, without any actions from the driver. That is why he installed Ecosense Trailer Assist on all three of his new Scania trucks in September 2019. Now, almost five months later, the fuel consumption numbers are in: a reduction of three percent.

Magnus himself is content that his intuition was correct; that an automatic system could reduce the fuel consumption even though his drivers had always been trying to adjust the spoiler as well as they could before.

Magnus elaborates: “Some of the drivers at first thought that the spoiler was set slightly too low by the automatic system, but measurements confirmed that it was actually in the correct position. This confirms how difficult it is to set the spoiler by feel; you often tend to set it a bit too high.”

“I actually believe that the fuel savings will become even greater over time. This autumn has had quite bad weather with lots of wind and rain. This usually increases fuel consumption a little bit. Apart from the fuel savings it is also very comfortable with a fully automatic system, I have completely forgot about all the manual cranking of the roof deflector! I really do believe fully in this product.”

The three trucks using Ecosense Trailer Assist are driving mixed routes. One truck usually travels between Finland and Norway to leave and collect new trailers. Fairly often the way home can be without trailer. Another truck mainly drives in Finland with trailers that vary in height between 420-450 cm.

Ecosense Trailer Assist helps the hauler in achieving the lowest possible fuel consumption and emissions at every moment in time. Additionally, it releases the drivers from their time-consuming task of adjusting the roof air deflector after each load carrier change – an adjustment that can also be difficult to get fully right without the automatic system from Rumblestrip.


More information

Milad Pouyanmehr, Rumblestrip, +46 76 760 74 03,

Magnus Wiklund, M. Wiklund Transport, +358 50 061 7871,

Bengts Åkeri reduced fuel consumption by 6%

When Bengts Åkeri in Örebro Sweden mounted Ecosense Trailer Assist on the roof air deflector on one of their semi trucks, fuel consumption decreased by as long as 6 percent. In addition to lower fuel cost, it also means lower carbon dioxide emissions. Doubled the savings automatically without the involvement of the driver.

Ecosense Trailer Assist is an upgrade package to existing roof air deflectors on trucks. It automatically sets the angle of the roof air deflector to an aerodynamically optimum position, without the operator having to do anything. This reduces air resistance, which lowers fuel consumption and emissions.

“I was first a bit skeptical about the installation on this particular truck. Partly because it is a truck with a small roof air deflector, partly because we did not think that the truck changed the trailer height especially often. But a decrease of just over six percent speaks its own language. Spontaneously, I think we have more trucks in operation that can save even more fuel, says Håkan Johansson at Bengts Åkeri in Örebro AB.

As one of the test companies with a field-tested system, Bengts Åkeri has mounted Ecosense Trailer Assist on a Volvo FH Globetrotter XL tractor truck. It changes daily between a 4.0 meter trailer and a 4.2 meter.

Ecosense Trailer Assist has a huge potential to help the haulage companies to reduce their fuel costs and emissions. Ecosense Trailer Assist is not only limited to tractor vehicles. Swap body and load-shifting trucks that shift flatbeds and containers can also reduce fuel consumption with properly adjusted roof air deflector.

– Through our partnership with KG Knutsson, Ecosense Trailer Assist is now available in the entire Swedish market. And in the near future we are aiming for Europe at large, says Stefan Strömstedt, Sales Manager at Rumblestrip AB, who developed Ecosense Trailer Assist.

“When Rumblestrip suggested that we test Ecosense Trailer Assist on this truck, I was, as I said, skeptical. At the same time, I know from experience how important the air resistance is for fuel consumption. That it performed this good shows that it works. The next step will be to check how many more of our trucks can save fuel with Ecosense Trailer Assist, says Håkan Johansson.

For more information:

Milad Pouyanmehr, CEO Rumblestrip AB, 076-760 74 03,

Håkan Johansson, Bengts Åkeri i Örebro AB, 0703-78 37 85,

More about Ecosense Trailer Assist at

Almi Invest invests in Rumblestrip

Almi Invest invests in Rumblestrip which reduces emissions from heavy trucks.

Almi Invest invests SEK 3 million in Rumblestrip, which develops products and services that reduce fuel consumption and CO2 emissions by up to 8 % in heavy trucks. The newly emitted shares, worth a total of 5 million, are also invested in by the company’s founder Gustav Kristiansson and former NHL professional Johan Franzén.

Heavy trucks account for about 10 % of Europe’s total CO2 emissions. Linköping company Rumblestrip has recently launched a software and a completely new type of automatic system for existing roof deflectors that reduce fuel consumption.

-Rumblestrip has developed a smart technology to help the environment in a concrete way, while the transport industry can save big money, says Pär Carlshamre, Investment Manager at Almi Invest. The importance of reducing CO2 emissions is becoming more important for each day. The potential for the technology is great and the team strong, we look forward to being part of the company’s journey into the global market.

Rumblestrip’s system, Ecosense Trailer Assist, attaches to the roof deflector on the roof of the truck cab and reduces the air resistance. Rumblestrip’s software solution optimizes the setting automatically based on weather, wind and size of trailer. Given the reduced fuel consumption, an average rider will have a return of investiment of about 24 months for each truck and save about 5 tonnes of CO2 per year.

The investment will be used to expand the market presence in Europe. The company has a number of patents granted, both in Sweden and Europe, and a large number of applications are being processed, including the USA, China and Brazil. Heavy duty vehicles account for 75% of all transportation within the EU and is projected to increase by 4 % annually given increased urbanization, e-commerce and special transport. There are about 1.8 million tractors in the EU and about 230,000 new ones are sold every year. About 95 % of these have a permanently installed roof air deflector that today needs to be manually adjusted.

-This is just the first step in our entry into the market for fuel and vehicle optimization. We are now establishing strong ties with the major players in Europe and are planning to launch our product as an option for new truck purchases shortly, says Rumblestrip’s CEO Milad Pouyanmehr. Having both software and hardware on board the truck puts us in a very exciting position, where we see great opportunities for additional sales.

For further information contact
Milad Pouyanmehr, CEO of Rumblestrip, tel. 076-760 74 03, email

Pär Carlshamre, investment manager Almi Invest, tel. 070-479 00 88, email

Gustav Kristiansson, Chairman of the Board of Rumblestrip, tel. 070-876 67 68, email

Maria Kessling, Head of Communications Almi Invest, tel. 076 880 88 10, email

Stefan joins Rumblestrip as head of sales

Welcome Stefan Strömstedt! As head of sales Stefan will focus on the launch of Ecosense Trailer Assist for the aftermarket.

Stefan’s extensive background and connections from the trucking industry is a huge asset for us, says CEO Milad Pouyanmehr.

Contact Stefan using the contact form on the website if you are interested to know more how Rumblestrip Ecosense Trailer Assist can reduce your trucks fuel consumption and CO2 emissions.

Rumblestrip receives 5.6MSEK (€500K) in funding!

The Swedish Energy Agency today informed us that they have awarded us with 5.6MSEK in funding. The funds are to be used to finalize the commercialization of the Ecosense Trailer Assist which will be released on the market in Q3 2019.

We are thrilled over the agency’s trust in us and our ability to reduce heavy trucks need for energy by 3% when using Ecosense Trailer Assist. And we are extremely proud to have passed all interviews, gates and demanding due diligences performed.

Today is another good day!