Here you find the full

Conversion process

for our Mercedes Vario 4x4 from a flatbed to an expedition vehicle

Our project started in 2015 with a discussion on how to travel the silk road, when we would have more time to travel. Until then we had been enthusiastic motorcycle travelers for decades. But we realised quickly that for such a long travel we would better have 4 wheels instead of 2. And so the idea of an expedition vehicle was born.

How it began

During winter 15/16 we got finally infected with the "expedition vehicle virus" by the beautiful book "Off the road", followed by many discussions about the concept, the pros and cons and the budget. It is an important phase because you decide on your future home for a timespan of 5 - 10 years. In February and March 2016 we visited several manufacturers within a 400km radius around Zurich (Bimobil, Exploryx, Woelcke). When conversion starts, several on-site discussions would be necessary, so it is good to have the builder in a 3-4 hours reach. Woelcke in Heimsheim/Germany was the best choice for us. The quality and the experience is impressive. But lots of patience is needed. At that time Woelcke had already over 2 years waiting time until delivery (today it is even more). But this has one big advantage: The conversion would start in autumn 2017, so we had enough time to optimise the box concept and did not need to decide too quickly.

Iveco Daily or Mercedes Vario 4x4?

We took a quick decision on the chassis. From the currently available new chassis on the market, the Iveco Daily was the best option for us with a weight of up to 7.2 tons, enabling an alcove concept. However, the 7.2 ton version was only available with 4x2, so we would need the expensive Achleitner 4x4 package. Our vehicle would look similar to that on the picture. The Achleitner 4x4 solution has a higher ground clearance, but the offroad capabilities are still limited due to the small tires. Furthermore, the overall impression was not very exciting, as the vehicle would still look like a "normal camper".

In March we started to prepare for the truck driving licence. For vehicles over 3.5 tons to 7.5 tons gross weight you need a European driver license C1/D1. In April we passed the theory exam.


The Iveco Daily was still our our first choice for a new chassis, but our dream was to have a real 7.5 ton truck like the Mercedes Vario 4x4. But production of the Vario ended in 2013 and the chances to find a good used Vario are low. Of course, there are some heavy trucks available downsized to 7.5 tons, like a Mercedes Atego or a Unimog. But it is not possible to realise an alcove with these vehicles. In addition, the payload is low, as these vehicles are built for over 7.5 tons. The search for a good Mercedes Vario 4x4 was very challenging as 4x4 Vario's with little mileage are rare. On the Internet you find Vario's with remarkable mileages of more than 500'000 km. Suddenly we got a call from Mercedes in Lucerne: This Vario 4x4 was for sale.

But: 160'000km mileage in only 3 years, because it was in daily use as a milk truck. Moreover with a short wheelbase (3.7m) and in very poor condition (lactic acid can be aggressive). In addition, the chassis was very stressed by the torsion movements of the milk tank. We estimated total repair and conversion costs -including wheelbase extension to 4.25 m - and then scrapped this idea.

Working on our to-do lists

We made our driving lessons on a Mercedes Sprinter bus with 17 seats and a total weight of 5.3 tons. We passed the practical driving test in the first go. Such a truck driver licence is quite expensive. We paid over EUR 3'000 per person (learning material, medical examinations, theory test, practical driving lessons and final test). Welcome to Switzerland :-).


In May 2016 we visited the 4x4 trade fair in Bad Kissingen / Germany (the largest offroad trade fair in the world by the way). Always good to see other vehicles to get new ideas and to rethink your concept. For us, this visit provided clarity in several aspects:

  • First we wanted a LPG-free design and an induction cooker. Cons: power usage, no oven (too much power consumption), high battery capacity (weight and cost of lithium batteries), special induction cookers, and the Omnia oven does not work with induction. So at the end we decided for a LPG solution.
  • Fridge: A compressor fridge by Kissmann is first choice.
  • Shock absorbers: Due to the vehicle's height, the vehicle is more exposed to swing movements while driving. The original shock absorbers are not appropriate to handle these movements. We therefore decided to install stronger shock absorbers from Marquart.  
  • Windows: There is still no alternative for the very expensive and heavy KCT windows. And they are really expensive, believe us, but the quality is outstanding.
  • Blackwater: Blackwater tank versus cassette toilet versus composting toilet? Still not sure.

Surprisingly Achleitner announced in May, that a new 4x4 offroad version of the Iveco Daily would come to the market, with larger single tires and higher ground clearance (see prototype picture below). The vehicle would be presented at the IAA trade fair in September. We were excited and changed our plans from the Achleitner allroad to the offroad version. But there was one major problem: The offroad version would only allow for 6 tons because of the single tires. That would limit our layout plan drastically. An alcove wouldn´t be possible due to the weight.

A telephone call to buy our Mercedes Vario 4x4

We looked forward to the IAA trade fair in September 2016 and the presentation of the Achleitner offroad prototype. But we still hoped to find a good Mercedes Benz Vario 4x4. And then we surprisingly found a very well maintained ex-army vehicle in the internet with little mileage in the Stuttgart area. This Vario 4x4 had a double cabin (which we would not need) and a flatbed (which we could sell). We scrapped the plans with the Iveco and purchased the Vario 4x4 immediately on the phone, only based on pictures (never did this before ;-). Now the task was to import the Vario to Switzerland.

Our Vario is an ex-army truck, registered in 2011 and in service until March 2016. We were lucky because usually army vehicles are being used for many, many years. Our Vario 4x4 was very well maintained by the army and only had 41'500 km on the odometer. From CTM, the company which built the flatbed, we got a picture showing our Vario with the Bundeswehr logo.

For our conversion project the flatbed will be removed and the double cabin will be shortened to a single cabin. Instead of 7 only 3 seats will remain.

After a final check we took over our Benny in August 16 from the Mercedes dealer in Germany and drove him to our home in Switzerland. Happy new owners ;-)

The 260km back home was a first great experience with our Benz: A real truck feeling, combined with a good overview over the street and a powerful engine. The registration formalities at the border were easy. We directly drove our Benny to Mercedes in Lucerne to prepare him for the Swiss vehicle inspection.

After two weeks Benny got his "Swiss citizenship". The vehicle inspection was carried out without any issues. No surprise after being checked by (1) TÜV Süd, (2) Mercedes in Stuttgart and (3) Mercedes in Lucerne to ensure all Swiss standards. But importing a truck to Switzerland is an expensive exercise. We paid more than EUR 4000 for the EU conformity declaration by Mercedes Switzerland, the preparation for the vehicle inspection and the border procedures. Now Benny was ready for the winter break in a barn before the transfer to Stuttgart again in spring 2017 for the start of the conversion work.

Out of curiosity we checked with Achleitner about the Iveco Daily offroad version and why no prototype was shown at this year's IAA trade fair. Answer: The project was cancelled. So good that we decided for the Mercedes Vario.

The conversion work starts

So in February 2017 we started the engine to bring Benny to Woelcke in Stuttgart. Ignition key was turned, and: After 6 months of winter break the engine started without any issues. What a sound and a feeling!

At the border we handled the customs formalities, as the Vario will now be "improved" in the EU for the next 12-15 months. You have to be very careful to avoid any tax consequences when bringing the "improved" vehicle back to Switzerland. But there are import/export agencies at the border to help you with these complex procedures.

After a 250km drive we arrived at the glory halls of the Woelcke company in Heimsheim (near Stuttgart). We discussed the work to be performed and left our Benny with Woelcke.

After having contacted several truck dealers for their interest in buying the flatbed, the flatbed went for little money to scrap dealers (the aluminum can still be used).

In spring 2017 Woelcke did the following prep work:

  • Removal of the flatbed
  • Shortening of the double cabin to a single cabin
  • Inserting a 30mm fiberglass rear wall

Prep work on the chassis

In August the work on the chassis started.


Engine / gearbox / tires

  • New front protection plate for the engine, because the Mercedes Vario unfortunately has a plastic oil pan
  • Replacement of the standard valve by a Rölex valve to protect the oil pan
  • As it is too expensive to replace the shorter gear transmission through a longer gear transmission (to reduce rpm) we decided to install larger Michelin tires XZY 9.5 R17.5, which are still approved by Mercedes Benz

Driver cabin

  • Removal of the flooring and replacement with noise-reducing materials
  • Burglary protection for driver and passenger doors

Chassis optimisation

  • Sandblasting of the chassis, anti-corrosion treatment and new painting in black
  • Sandblasting of the tire rims, anti-corrosion treatment and new painting in black
  • Heavy duty shock absorbers by MARQUART, to reduce swing movements of the vehicle while driving
  • Triple leaf springs on the front axle instead of double leaf springs
  • Removal of the heavy trailer hitch and of all power connections to the trailer to save weight
  • Removal of the spare tire holder under the chassis, as spare tire will be placed on the back side of the box
  • Exhaust: moved forward to make room for an additional diesel tank and pipe lifted to improve ground clearance

Pictures before chassis painting

Pictures after painting

Larger tires

We replaced the tires sized 215/75 R17.5 by new Michelin XZY 9.5 R17.5. These new tires are designed for onroad and offroad. In addition, the tires have an approval for use during winter. On the other side: New rims 6.75 x 5.17 were required. Rims were painted in black.


Important: This tire size still has the official approval by Mercedes Benz.


The following pictures illustrate the size difference to the old tires. As a result, with the new tires we achieve nearly 4 cm more ground clearance and a 10% reduction in rpm.


Next phase: Metalworking

In September 2017 Woelcke started with the steel subframe. This subframe also includes a sliding frame for the mechanical outside ladder. This ladder is made of aluminium. Pictures of the subframe (not yet galvanized) and the already completed outside ladder below:

Then in October the subframe was galvanized.

In November the construction of the habitation box started and the bottom plate as well as the side walls were ready. Furthermore we took decision regarding our toilet system. Because it makes no sense to flush filtered water through the toilet, we decided for a Kildwick composting toilet instead of a water-flushing toilet. This not only saves electricity, water and weight, but also facilitates the dumping process. 

Building of the overcab habitation box

The habitation box was ready in December 2017. Some facts about the box construction:

  • 50mm sandwich panel construction with 2mm fiberglass on each side
  • 60mm floor plate, same sandwich panel structure as for the walls and ceiling

In January 2018 the vehicle was transported to Brixner to get its painting in RAL color 7032 grey. For the painting all removable parts of the driver cabin were removed (doors, hood, windshield) and all hollow spaces got a special anti-corrosion treatment. 

In February the chassis was married with the habitation box. A big event, and for the first time we realized how tall our vehicle will be. 


Based on the floorplan, Woelcke made a first furniture prototype in December 17. With this prototype we were able to shift the sidewalls a bit left or right, until we reached a final position. This final layout sets the frame for the furniture production.  

Furniture production started at the beginning of 2018 with the kitchen block. All fronts have an oak laminate.

Toilet and bathroom

We decided for a KILDWICK composting toilet to avoid the search for dumping stations and to save water. The solid waste goes into a composting bucket and the urine goes into a separate 40 litres tank. The shower is separated from the bathroom (dry bathroom).


In the kitchen we use quality devices from CAN (3-burner gas cooker) and KISSMANN (compressor fridge)

Energy management

Power supply comes from 300 watts solar on the roof.  Battery storage is 2 x 160 Ah in Lithium-ion technology. Furthermore we have a 24kg LP gas tank only for cooking. Heating is done with a TRUMA diesel/electricity heater. 

Diesel and water tanks

Tanks are all self-made by Woelcke. Pictures show the fresh water tank, the grey water tank, the urine tank and the additional diesel tank. Together with the standard diesel tank, the diesel capacity will allow us to go for more than 1000 km. 

Windows and roof hatch

We decided for KCT windows, which are very heavy and expensive, but have the highest quality also in high altitudes. Window frames are painted in the same colour as used for the body. There is also a KCT roof hatch in the alcove.

Outside storage boxes

Our Benny has 4 storage boxes under the ladder frame, all self-made by Woelcke.

WLAN communication

We use a BATLINK travel connector with a 74cm mobile antenna and a reach of 3km to have access to WLAN networks.

Additional headlights

To improve the light power of the Mercedes Vario, our Benny has 2 additional HELLA LED headlights with a Ref value of 40 each. The headlight carrier is powder-coated. 

Finishing works

Some finishing details, like chequer plates for the wheel arches, the garage and the front protection.

Final works before handover

End of March 18 our Benny is 99% done. Some minor things still to do like the mirror in the bathroom, entrance steps and fenders.

Some further technical improvements in April: For example, stronger shock absorbers from MARQUART are mounted (to avoid swing movements of the body while driving) as well as an oil drain plug from RÖLEX (to protect the thread). Furthermore a diesel filter from SEPAR is installed to protect the engine from bad fuel. In our storage compartment there is now a mobile compressor to adjust the tire pressure.

Testdrive by Woelcke before the handover in April:

Handover was on April 18, 2018 and we were very happy to drive Benny to its new homebase in Switzerland.

Still some things to do

Before our first roadtrip with our Benny, we have to visit the Swiss vehicle inspection to get the vehicle approved for Switzerland. After the inspection (lasting 1,5 hours) we received the Swiss vehicle registration.

One more thing to be done: As our Mercedes Vario was registered as a truck in his former life, the speed limit is electronically limited to 89 km/h. With the registration as an RV this speed limit can be removed. However this can only be done by Mercedes Benz with a special electronic code.

Now finally we can move into our new home on wheels.

Videos about the "making of"