So, I had a 90km each way trip today and about 70km of that was highway with neglible sea level difference.
Felt in a very scientific mood, so I did an A-B test on the highway.
A: Driving up to 170km/h where safely possible on the open road and up to 130km/h in the tunnels while keeping at least a 2 second distance behind the vehicles upfront. Tried to use as little brakes as possible, but still had to brake a lot due to lane changers who forget their turn signal before they go on the speeding lane.
Result: average speed of 123km/h and a fuel consumption of 7.2litres/100km.
B: Driving up to 140km/h on the open road and 110km/h in the tunnels.
Result: average speed of 114km/h and a fuel consumption of 5.2litres/100km.
The car was a Renault Laguna 1.5dCi with A/C on all the time and the stereo blasting Helix through 9 speakers
I didn`t expect a big difference in average speed or the fuel economy, but going only 8% faster for 38% more fuel has been a hit in the face. Not to mention driving slower has yet again proved to be more relaxing because I almost never had to use the brakes.
So, speeding does save time on an empty road, but in average traffic conditions it is only up to a certain point that you are rationally saving time, beyond that it is only a hazard and a big no no for both your wallet and your nerves
