Eco-safe Driving Information

Thanks for visiting. This is our free resource for drivers and trainers who are using our Eco-Safe driving pads. This product is approved by the Energy Saving Trust as an aid for those learning eco-safe driving technique. Eco-safe driving, or just ‘Eco Driving’ means adopting a driving style that will reduce damage to our environment and improve safety on our roads.

Being an eco-safe driver means you have developed your skills in hazard perception, anticipation and defensive driving so that you reduce fuel waste, pollution and accident risk. Remember the magic triangle!

Qs: 
Which is better - petrol or diesel? What about bio-fuels?
I have an electric vehicle or drive a hybrid - is eco-safe driving for me?
 
When buying a vehicle, your choice of engine/fuel type may be influenced by local, national or global concerns. However, whether your vehicle is powered by fossil fuels, biofuels, electricity or is a hybrid, adopting eco-safe driving techniques will still reduce the environmental impact of your driving and the cost of vehicle ownership. 

ANTICIPATION

A ‘stop-start’ driving style involving harsh acceleration and braking is really uneconomical, environmentally unfriendly and stressful for driver and passengers! Eco-safe drivers avoid these issues by: Scanning the road ahead and behind; 'fitting in’ with traffic flow; using acceleration sense and ‘engine braking’ when it is obvious that they will have to slow down or stop; keeping a safe following distance so that they can react safely to changes in traffic flow; having patience and consideration for others in congested and slow-moving traffic; maintaining progress at junctions, adjusting their speed on approach to avoid unnecessary stops.

Q: What should the eco-safe driver anticipate with changes in gradient or road surface conditions?

Gradients and changes in road surface conditions will always affect stopping distance. The good driver will adjust their speed and distance to the vehicle ahead so that they can continue to use eco-safe driving technique. For example, going downhill you will need to increase the distance between you and the vehicle ahead and when slowing to stop will need to use acceleration sense and engine braking earlier than on a level road. Similarly, should it start raining on a level road, you know it will take longer to brake to a halt - so adjust your distance to the vehicle ahead and apply your eco-safe driving skills of acceleration sense and engine braking earlier than for dry conditions.

USE OF GEARS

All gears can be used at a range of speeds. The eco-safe driver uses gears efficiently to reduce energy waste. Take control when building up speed by avoid harsh acceleration, engaging higher gears as soon as you can and using block gear changes when appropriate. 
 
Take control when slowing down by anticipating and using acceleration sense: Avoid harsh braking, use block gear changes when appropriate and engage lower gears at appropriate speeds.

 

Qs: What is ‘engine braking’? What is ‘acceleration sense’?

Acceleration sense means gentle use of the accelerator pedal to speed up and easing off it in good time to slow down rather than using the brakes. Easing off the accelerator pedal means that the engine or motor will slow through natural resistance in the absence of power flow. This is known as engine braking.

Qs: I drive an ‘automatic’. How does ‘use of gears’ apply to me? Why doesn’t ‘use of gears’ apply to electric vehicles?

With automatic transmission, the vehicle changes gear in response to speed and load on the engine. So harsh acceleration will delay an upward gear change and harsh braking delay a down shift. Both are wasteful of fuel so eco-safe technique is just as valid for 'automatics'. The motors of electric vehicles vary very little in efficiency over large speed ranges so there is no discernible advantage to having gears. Electric vehicles typically have only a choice of  'Drive' and 'Reverse'.

USE OF SPEED

The eco-safe driver  will aim to fit in with traffic flow and volume. Heavy traffic flows more freely when drivers adjust speed to match the carrying capacity of the road. This is the principle behind 'smart motorways' where a variable speed limit makes best use of the available capacity. Remember that speed limits are not targets!

Qs: What wastes fuel at lower speeds? Why is air resistance so wasteful at high speed?

Lack of anticipation, erratic use of the foot controls and failure to make best use of gears are the main will all result in fuel wastage. Changing up gears at the earliest safe opportunity is the key skill the eco-safe driver will use to save fuel at lower speeds. At higher speeds you should be aware that air resistance (drag) increases with the square of speed. An increase of speed by 10 mph over 60 mph can increase petrol or diesel consumption by up to 13%.

ENGINE BRAKING

Internal combustion engines and to a lesser extent, electric motors, all have to overcome compression and/or friction forces to work. Engine braking simply means using these retarding forces to help us slow down so that we don‘t have to rely so heavily on the brakes.

Qs: Should I ‘use gears’ to slow the vehicle? Does ‘coasting’ in neutral save fuel? What about automatics, hybrid and electric cars?

Changing to a lower gear too soon with the aim of slowing the vehicle will waste fuel. It is better to anticipate changes in the road/traffic conditions and use acceleration sense, changing down gears to match the ensuing road speed. In neutral, the engine runs at tickover speed and you would naturally think this would result in minimum fuel consumption.Think again! As you slow down (especially in an automatic) the engine struggles trying to maintain tickover speed when vehicle speed doesn't need it.What if you need to accelerate suddenly? Then you will take time to engage gear or select 'Drive' - result, harsher use of the accelerator! Electric cars (and some hybrids, according to configuration) don't coast! taking your foot off the accelerator feels like pressing the brake as the motor uses the car's motion to regenerate electrical energy.

 

ECO-SAFE BUBBLE

 

 

 

The clear space you need around your vehicle to be able to drive in an eco-safe way is known as your ‘safety bubble’. The faster you go, the longer and wider your safety bubble must be! Anticipation, defensive driving and acceleration sense are key to maintaining this important safety margin.

 

 

Qs: What else could mean having to maintain a bigger safety bubble? What should the drivers of cars A, B and C do in order to maintain their eco-safe bubbles?

Anything that could increase your stopping distance will that the size of your safety bubble will increase. These could be changes in surface conditions such as loose gravel, a wet road or ice. 

Going downhill means that your forward safety zone must increase.

Feeling a little 'under the weather' ? If you can't avoid having to drive when your concentration is suffering, your safety bubble will need to be larger.  

Remember that you must always be able to stop safely in the distance you can see to be clear ahead. So, if  visibility is reduced by fog for example, you will need to slow down so that your safety bubble is within the space you can see to be clear.

In the diagrams: Car A needs to drop back (slow down!) so that the green car stays beyond the safety bubble. Car B also needs to slow down - this will give the close following driver opportunity to overtake without having to cut in sharply ahead: Car C can't possibly get through the gap at the same time as the approaching bus. So the driver of car C should slow down and stop if needed to let the approaching vehicle through.

 

 

EVERY LITTLE HELPS

How do the following affect fuel consumption?

Air conditioning systems, like fridges and freezers, use heat pumps to pump a fluid around a circuit. The compressor that drives the movement of this fluid takes its power from the vehicle engine, increasing fuel consumption. Using air conditioning on a short journey can have an alarming effect on fuel consumption - using over 20% more fuel to get the ambient temperature of the car interior to a comfortable level. On longer journeys the air-conditioning will not need to work so hard to maintain the set temperature but you can still expect to use 5% more fuel than the same journey without Air-conditioning. Hot day and hot interior? Open the windows and let some fresh air flow!
 
Under-inflated tyres have a bigger 'footprint' in contact with the road. This in turn increases rolling resistance and fuel consumption. Pressure being too low by 10% on all four tyres would probably increase fuel use by 1%. A 25% deficiency in tyre pressure would cost you 2% in fuel!

'Eco mode' switches the engine off when you brake to a halt. The main purpose of eco-mode is to reduce pollution in congested urban areas. It is true that an engine uses more fuel per second during starting than when the engine is idling. Nevertheless the benefit of the engine not running far outweighs the losses in the stop-start cycle. 

Roof racks and roof boxes have relatively little effect on fuel consumption when driving around town at low speed. However, at higher speeds expect fuel use to increase by 15-20% with an  empty roof rack and up to 40% if you have it loaded with cases or carry a roof box!

 Physics says that carrying excess weight in your vehicle must use more fuel. The major impact is on overcoming inertia to get the vehicle moving from stationary. At worst, a boot full of garden compost might cost you 0.5 - 1% in fuel. Not a lot but add that to the fact you forgot to check your tyre pressures and that eco-mode is too irritating to use...

 

...every little really does help!