This Christmas (December 23) my wife Tricia, daughter Margaret and I headed from Hingham, MA to join our son and his family in Towson, MD in our 2009 Prius. Sharing the driving as we were, we each ran the Waze application on our iPhones — a profligate overuse of cell data, I know! We figured out that Waze calibrates travel times based on the user’s history of driving speeds. Tricia always drives faster (~70 mph) then I do (~55 mph) and Margaret is always bumping up against 80 mph. No wonder Waze says she arrives 20 minutes before Tricia and 40 minutes before I do. That got me wondering how much more petroleum and carbon emissions would Margaret’s 40 minutes of “saved” time actually cost over my so-called ‘slow’ driving? I found that contributors to the Ecomodder Forum had developed and refined an “Aerodynamic & rolling resistance, power & MPG calculator” that could help me come up with an answer. Read my substack autocar - "speed what is it good for?" for the full answer and see a useful graph here: and another here. Hope you enjoy. John Daly
Nice work. I have discovered the same my driving style and best MPG is at 60mph. Depending on what roads im on I try to stick to that without being killed by speeding cars. I watched a interesting video on the Cannonball run most recently won by a guy in a Gen 4 Prius. He first tried 3 gas tanks and drove really fast. like over 100mph but ran out of fuel before Denver. The next year he set the record averaging 84 mph I think on the same amount of fuel. Shows that after a certain point wind resistance is too much. Like a Lamborghini with a full gas tank running at top speed of 203 mph will be out of gas in an hour. LOL Thanks for the read.
Bah, that's old stuff. A Bugatti Chiron, while making 261mph, will empty its (100L / 26.4 US Gal) tank in 9 minutes.
Yes after a certain point you are spending almost all your energy just to push air ….not to speed it forward. “Make haste slowly” as they say.
Ah that explains why this clip is only 3 minutes long Interestingly Germany just rejected a plan to abolish the unrestricted stretches of autobahn due to fuel prices and environmental concerns: https://www.cleanenergywire.org/news/german-transport-minister-rejects-autobahn-speed-limit-after-report-shows-climate-benefits The government believes that high fuel prices will encourage people to drive more slowly, however...
