Real and useful tips on saving fuel cost and environement

Lets take average family car Volvo V50 Diesel 100kW. On highway it is supposed to take 4.6 l/100km (50 MPG) and this is exactly what computer says while cruising 90km/h.

I tried out to cruise 90km/h behind big truck. This reduces air drag and the closer you are the less the resistance. Distance between truck was bit less than usually driving on highway but still long enough to react after sudden breaking. After-all small car breaks are better than fully loaded truck ones.

Result was that mileage increased significantly and computer was showing 3.5 l/100km (67 MPG).

Another way of reducing fuel consumption is to just drive slower. Reducing speed from 90 km/h to 80 km/h will bring fuel consumption down to 4.2 l/100km (56 mpg) and further slowing down to 70 km/h gives result of 3.8 l/100km (62mpg). Of course slowing down takes you longer drive to destination.

If driving 80km/h then after one hour you have still 10km to go which takes you 7.5 minutes. For 70 km/h it takes you 17 more minutes to drive 90km distance. Given diesel fuel costs 1.3EUR per liter then driving 90 km at each speed costs 5.4EUR, 4.9EUR and 4,4EUR. You can consider that you are payd 4EUR an hour for driving that additional 7.5min with 80km/h. For 70km/h your salary is 3.5EUR/h per extra hour spent on road.

Why go speeding at all?