Fuel economy at different highway speeds
Posted: April 3rd, 2006, 11:13 am
Last week I drove from my home in kitchener, ontario to beautiful montreal, quebec, approximately 600 km away (375 miles).
During the trip I knew I would be filling up on gas a few times so I decided to calculate my MPG at different sustained highway speeds. On the way there I drove during the night (8pm->3am). Not much traffic and could afford to drive at higher speeds. On the way back I drove during the day, it was nice and sunny and I wasnt in any rush so for the purpose of the experiment I drove the speed limit (100kph/62mph). Below are the speed brackets of sustained highway speeds and their respective fuel economy rating.
100kph / 62mph = 38 MPG
130kph / 80mph = 30 MPG
150kph / 94 mph = 26 MPG
170kph / 105 mph = 24 MPG
The highway is very hilly and it was quite windy. During the tests I sped up down hills and tried to ease off the gas uphills so that my target speed was maintained as i crested the top of the hill. I am confident that I will be able to reach 40MPG on flat roads during less windy driving conditions.
Although driving the speed limit offered incredible MPG I doubt I will do that again. The driving was tedious, and at times felt unsafe when old ladies and transport trucks were passing me on the 2-lane highway.
When travelling at higher speeds I did have to slow down for trucks swapping lanes and then accellerate again to reach my target speed. This will damper the MPG. Trucks travel in packs driving closely behind each other so that they reduce their drag and increase fuel economy, they take turns being the lead truck, but pass very slowly.. trucks drive at around 110kph and they will pass each other at 112, on a 2 lane highway this blocks off the lanes for a couple minutes as one slowly passes the other and I got stuck behind trucks more then a few times.
Overall the driving was pretty uneventful.. and running the MPG readings was the only thing I had to cut through the boredom. Its funny what little games you come up with in your head when you have to drive for 6 hours straight.
During the trip I knew I would be filling up on gas a few times so I decided to calculate my MPG at different sustained highway speeds. On the way there I drove during the night (8pm->3am). Not much traffic and could afford to drive at higher speeds. On the way back I drove during the day, it was nice and sunny and I wasnt in any rush so for the purpose of the experiment I drove the speed limit (100kph/62mph). Below are the speed brackets of sustained highway speeds and their respective fuel economy rating.
100kph / 62mph = 38 MPG
130kph / 80mph = 30 MPG
150kph / 94 mph = 26 MPG
170kph / 105 mph = 24 MPG
The highway is very hilly and it was quite windy. During the tests I sped up down hills and tried to ease off the gas uphills so that my target speed was maintained as i crested the top of the hill. I am confident that I will be able to reach 40MPG on flat roads during less windy driving conditions.
Although driving the speed limit offered incredible MPG I doubt I will do that again. The driving was tedious, and at times felt unsafe when old ladies and transport trucks were passing me on the 2-lane highway.
When travelling at higher speeds I did have to slow down for trucks swapping lanes and then accellerate again to reach my target speed. This will damper the MPG. Trucks travel in packs driving closely behind each other so that they reduce their drag and increase fuel economy, they take turns being the lead truck, but pass very slowly.. trucks drive at around 110kph and they will pass each other at 112, on a 2 lane highway this blocks off the lanes for a couple minutes as one slowly passes the other and I got stuck behind trucks more then a few times.
Overall the driving was pretty uneventful.. and running the MPG readings was the only thing I had to cut through the boredom. Its funny what little games you come up with in your head when you have to drive for 6 hours straight.