Ecological Car Improvements, Fuel Efficiency with Old Cars

Much has been said about next generation motorcars and the influx of bio-fuels, petrol electric hybrids, pure electric, hydrogen power and so on.  Still, just how much improvement they make to the environment on a total carbon footprint basis remains debatable. But we can do something about what we have now. This article looks at what can be done to improve existing motorcars – both old and new - in terms of fuel efficiency. And we help illustrate what constitutes a modification requiring insurance provider notification.

By Andrew Porter

Engine Oil – A product that provides more than just a lubrication fluid for the engine. In fact, it contains many products to help clean the engine, and prevent sludge accumulation. Therefore, discoloured engine oil means that it is doing its job. However, how does this affect fuel economy?

Oil viscosity has an impact on fuel economy. The more viscous the engine oil, the more it requires to move, therefore, more energy is required with more fuel consumed. However, before rushing out to use low viscosity engine oil with the belief that it will improve fuel economy (and it will undoubtedly do so), there is the issue of optimising the oil viscosity to match the engine.

Oil viscosity needs to be low when the engine is cold and first starts, as the engine needs to have the oil circulating as soon as possible to minimise engine damage. However, when the engine is fully warmed up, it does not want the oil to be so thin that it is not protecting the engine. This is why the oil has viscosity modifiers added to provide the correct viscosity profile to suit the engine, and it is this viscosity characteristic specified by the car manufacturer.

The code used is typically SAE 5W 30 for an engine oil. 5W indicates that the oil has a viscosity rating of 5 at its lower operating temperature, 'W' being often taken to mean Winter, and 30 as its higher temperature. The higher the first figure, and the higher the second figure, the greater the viscosity of the oil. This means, for example, modern engines with a tighter dimensional tolerance in manufacture can use lower viscosity engine oil, and benefit from the improved ease of engine movement with improved fuel economy. For older engines, particularly in those cars made before modern precision manufacturing methods came into common use, they can use engine oils with a viscosity rating as high as SAE 20W 50.

Step 1 – Do not use engine oil with a viscosity rating higher than specified for the car, as this will cause the engine to use more fuel to overcome the additional frictional losses. Change the engine oil, and oil filter at the recommended intervals. Do not use oil additives, as modern engine oils already contain the required detergents, viscosity modifiers, and other related products.

Car Tyres – How can car tyres make a difference? Simple: rolling resistance. The lower the rolling resistance, the lower the frictional losses, and better the fuel economy. With my own car, just switching over to lower rolling resistance tyres gave me an additional 5 miles per gallon of fuel, or 1.1 miles per litre of fuel.

Step 2 – Select the correct size and type of tyre to suit your vehicle. Make sure that you choose a tyre designed to have a low rolling resistance. For example, Continental Tyres in Germany produce their ContiEcoContactTM3 specifically designed to reduce fuel consumption without compromising the performance of the tyre. Michelin produce their ENERGYTM saver tyre, again, specifically designed to reduce rolling resistance thus also fuel consumption. Always use the correct inflation pressure as this optimises the fuel efficiency.

Engine – Several elements, where there is now a divide between engines produced before electronic engine management, and those with full electronic engine management plus catalytic converter.

For older cars, the first, and perhaps obvious method is to have the engine tuned for maximum fuel economy without endangering the engine. In other words, if the fuel air ratio is too lean in favour of the air, the engine temperature can rise too high and risk damage. This means that tuning the engine requires a process of monitoring the idle engine revs, the exhaust emissions, and adjusting the fuel air ratio until the optimum exhaust gas emissions are measured, and the idle engine revs retain the correct value. In some cases, this means adjusting both the fuel air ratio, and the engine idle revs until the optimum balance has been reached.

The next step is a modification, and it only really benefits older petrol engines that do not have electronic engine management systems. The change is to fit an Ecotek CB-26P, a device that fits in the vacuum servo/breather hose to the inlet manifold. It is then tuned, which only requires hand adjustment with a warmed up engine running, to then be ready to use. It works by modifying the air flow into the engine as it creates an element of off-throttle turbulence making acceleration smoother and more urgent. This produces improved fuel economy, without loss of performance.

For modern engines, with full electronic engine management, the next best thing is Eco-tune.

Eco-tune is a means to overcome the compromises made within the car's electronic engine management system to comply with national restrictions between countries, or rather to cover a range of fuel energy ratings that differ between countries while retaining the use of the same engine between different grades of the same model car. This means that the efficiency of the engine detracts from the optimum for any given fuel energy density.

To overcome this issue, it is possible to have the engine remapped. What this means is that the engine control unit electronic module is reprogrammed to optimise the settings within the electronic control unit for the car, and the fuel. This results in improved fuel economy, reduced pollution, less burned fuel in the exhaust; in the case of diesels, less smoke, without invalidating the warranty or insurance.

Step 3 – For engines not fitted with catalytic converters that use petrol, optimise the engine tuning for the best fuel economy, without endangering the engine. Once tuned, consider fitting an Ecotek CB-26P. For engines with electronic engine management, diesel or petrol, consider Eco-tune to optimise the fuel economy of the engine, again, without endangering the engine.

Energy Drain – Powering items within the car, such as air conditioning, power assisted steering, audio equipment, lighting, headlights, etc., takes power. This power ultimately comes from the engine. When more power is consumed, the fuel economy reduces. This means that the more items you load the alternator with, the more fuel the engine must use.

Step 4 – Minimise, where practical, the electrical loading on your car. Where possible, and legal, replace light bulbs with Light Emitting Diodes or LED. These are 90% more efficient than conventional lights, and lasts 5-6 times longer. Do not use air conditioning unless necessary, accelerate gently, use the highest gear that the car can comfortably use against the road speed, and avoid stop-start routes as much as possible.

WARNING: Some of the suggestions made in this article may constitute a modification to the car. For this reason, before making any changes, check with your insurance provider. Items such as tyres of the same size and type as originally fitted but have a lower rolling resistance are fine. Tuning the engine is also acceptable. Using the best engine oil to suit the car and fuel economy is also acceptable. However, fitting an Ecotek CB26P may be taken as a modification, so may using Eco-tune. In many cases, as long as the insurance provider is aware of the change, and knows that it has been done professionally, there are no problems. If in doubt, ask.

 Useful Links

The following have been used in researching this article, and may be of interest for those wishing to consider the options detailed herein.

a)                                                Car Engine Oil information from Castrol

b)                                    Continental Tyre information.

c)                                                Michelin Tyre information.

d)                                    CB-26P fuel economy improvement details.

e)                                    Eco-tune details for modern cars.

f)                                    Light Emitting Diodes alternatives.


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