Motorhome running costs - saving money with fuel economy

More economical driving style

Motoring bodies are all in agreement about the heavy right boot effect on fuel economy. Excessive speed is therefore out and using a light right foot for gentle acceleration is essential for fuel-efficient driving. Driving in the highest-possible gear for your motorhome, at a moderate speed and changing up through gears as quickly as you can, with the lowest revs possible without the engine straining, is the ideal. More recent vehicles are fitted with an indicator to encourage the use of the most efficient gear to help with economy driving. With my 2.3-litre Ducato engine, this efficient gear tends to be with engine speed around 1,500 to 2,000rpm. Remember, the faster an engine spins, the more fuel it uses.

Anticipating the road ahead is an important aspect of safe driving, but also for adapting your driving to save fuel. Speeding towards a traffic junction and then applying heavy braking is not conducive to fuel economy, nor is sprinting away from traffic lights. Indeed, much fuel energy goes into overcoming the inertia of accelerating from a standing start.

If you look at performance graphs for engines, where torque and power produced is shown plotted against engine revs, there is always a sweet spot where the torque and power outputs increase to a peak then decline with further increases in revs.

The travel speed at which you will reach the most efficient level will depend on the gear you’re in and the amount of road resistance your motorhome offers, which will be related to the coefficient of drag and weight of motorhome. Clearly your motorhome will offer much greater drag or wind resistance than a sports car and the outline of most coachbuilt motorhomes can hardly be called aerodynamic. Most motorhomes are loaded up to their maximum weight, which increases drag through the tyres and the amount of power required to pull up inclines.

At one time, coasting was considered to be a way of saving fuel, but coasting out of gear is not acceptable as you are no longer in control. Also, coasting as such is no longer needed as modern fuel and ignition systems are controlled by the vehicle’s electronic control unit (ECU), so when you take your foot off the accelerator, the ECU cuts the fuel supply to the injectors.

It goes without saying that, when stopped with the engine idling, your fuel consumption is increased (it’s zero mpg) and could be considered to be illegal under rule 123 of the Highway Code and The Road Traffic (Vehicle Emissions) Regulations 2002.

Stop-start systems are becoming common on modern campervans and motorhomes, which deal with this situation, but be wary about using such a technique manually as vehicles with automatic systems have a heavy-duty battery and starter to cope with frequent restarting.

As encouragement with the light right foot approach, it’s worth considering the experience of MMM writers. Travel writer, Andy Stothert, has a reputation amongst his fellow writers for being ultra-fuel-efficiency conscious, religiously keeping his speed to around 56mph and records fuel consumption figures approaching 40mpg. In contrast, I have to confess that, with a long drive ahead of me on a quiet motorway in my similar panel van conversion, I can get bored and my right foot gets heavier and so my fuel consumption often doesn’t even approach 30mpg.

IAM RoadSmart says,

Some engines are more fuel efficient than others and modern engines tend to be the most efficient. We can’t reasonably consider replacing the engine, but tuning or ECU remapping systems for economy are available and diesel engines respond very well to tuning.

In the ultimate economy tuning situation you can take away power, but this needn’t be the case. Most economy tuning will provide some increase in power and torque, but just don’t expect the savings to be so big if you use the full range of revs and drive harder.

Viezu, a specialist engine tuning company, considers heavier vehicles, such as motorhomes, especially those with older and generally less efficient engines, to be likely to produce the best results from eco tuning. It also claims that, even with the most economical of 1.6TDI engines, 9% fuel efficiency savings can be achieved.

You need to inform your insurance company of any modifications, including tuning. Most motorhome insurers won’t penalise you, especially if you’re tuning for increased fuel economy.

Paul Busby, CEO, Viezu says,

Motorhome loading and wind resistance

So, the heavier the motorhome, the greater the fuel needed to shift the motorhome from a standing start and dragging the weight up gradients. Empty your motorhome occasionally to assess if all the accumulated kit is still needed.

Wind resistance can be a big factor in increasing fuel consumption and I’d expect a low-profile coachbuilt or panel van conversion to perform better than a taller motorhome with a luton and an overcab bed, but this is obviously difficult to define without designing complicated aerodynamic modelling systems.

You can’t do much about styling or the essential paraphernalia on your roof such as rooflights, TV aerials and solar panels. However, you may wish to reconsider any large roof storage box or rack, which is standing well above the usual roof clutter.

Motorhome maintenance and general usage

Regular servicing will help with fuel efficiency. Use the recommended oils, as they are likely to be high quality and minimise engine friction as well as extending the life of the vehicle.

Checking your tyre pressures is very important for safety and fuel efficiency. Underinflated tyres will increase friction with the road and be unable to support the vehicle’s weight and risk a blowout. Refer to your motorhome manual for the correct tyre pressure or use the TyreSafe website (tyresafe.org) calculator or contact the tyre manufacturer. You will need to know the tyre size and rating along with the motorhome maximum axle loadings to be able to work out the recommended tyre pressure.

Tyres now come with an efficiency label, which shows two classifications: one for wet grip and the other for rolling resistance designated with the letters A to E. Fuel-efficient tyres with low rolling resistance require less energy to roll, which translates into less fuel used, with A being the most efficient. Between the classes, fuel consumption increases by just 0.1 litre for every 100km (62 miles) driven. If you have camping tyres fitted then there is unlikely to be much choice available and so choosing a fuel-efficient tyre may not be an option.

TyreSafe says:

When driving, remember that using ancillary equipment can reduce efficiency. Air-conditioning (AC) will impose an additional drain on your fuel efficiency, although switching off the AC and opening the windows at higher speeds is also likely to increase drag. It’s best to have AC off and windows open at low speeds, with AC on and windows closed at speed.

Supermarket budget diesel or premium fuel?

Undoubtedly, supermarket fuels are cheaper than the large oil company brands, but in the past when problems have arisen with fuel blockages, it’s the supermarket fuels where blame is directed. However, I’ve yet to find any evidence of such problems being proved to have arisen from supermarket fuel. All the evidence indicates that supermarket fuel is the same as for the oil company brands.

All petrol and diesel sold in the UK must conform to European and British standards, EN228 for unleaded petrol and EN590 for diesel. In most cases, oil company suppliers and supermarket fuel comes from the same refinery.

However, there is a difference between supermarket fuel and the premium products of the oil companies, like Shell’s V Power, BP’s Ultimate products and Esso’s Synergy fuel. These premium products contain additives to help clean and prevent build-up of dirt in intake valves and fuel injectors in petrol engines, as well as the fuel injectors of diesel engines. Premium petrol may also be of a higher octane rating.

Don’t forget there are independent filling stations that offer prices competitive with supermarkets. To locate the best prices at your location, use one of several apps that are available, like petrolprices.com

Supermarket fuel isn’t always available when you want it, like on motorways, hence a locator map with fuel prices can be invaluable while on your travels.

The major oil companies do operate loyalty schemes whereby you accrue points with purchases, which can be used against future purchases, but whether it’s worth the hassle is a personal choice.

The AA says,

Use public transport

When you get to a campsite, using public transport (or bikes and feet) for short trips to explore and reach local attractions can be kinder on the wallet and the environment. According to the IAM, you use up to 100% more fuel in the first two miles than in subsequent miles.

Also, when leaving a campsite, don’t use the engine/cab heating to defrost windscreens or warm up the cab area prior to setting off. Plus, using an engine to charge up your leisure battery while parked up is not ideal, try to do this while on the road using a more efficient B2B charging system or invest in solar panels to top up 12V batteries without powering up the engine.

Summary: Top ten tips for economising motorhome fuel economy

• Drive in the highest possible gear and change up as quickly as possible
• Anticipate the road ahead and avoid heavy braking. Gently increase speed on approach to hills and ease off while ascending
• Shift into neutral at traffic lights while idling and allow stop-start to take effect if you have it fitted
• Consider an efficiency remap, as long as you don't make full use of the available extra power
• Pack lighter, does your motorhome need to be fully laden all the time and consider travelling with less water in the tanks, etc
• Service the motorhome regularly, using quality engine oils
• Check your tyre pressures, making sure you know the optimum pressure for your weight of vehicle and use more efficient tyres, if possible
• Consider your use of air-con when driving
• Use budget fuel to reduce the cost of a fill, but topping up with premium fuel every so often won't harm the engine, either
• Consider using public transport or walking/cycling to destinations/shops once parked up on a campsite

Got any more tips? Send your suggestions to [email protected] for possible publication in MMM, The Motorhomers’ Magazine...