6 ms·

Care to share some of those tips?

• nathancahill 11y ago
  Accelerate gradually, stay off the brakes.
  • kwelstr 11y ago
    And when in the highway don't go too fast, speed increases drag etc. etc.
    • lucaspiller 11y ago
      I did some tests on a long drive last week, for the Smart Forfour I had this was the fuel consumption. It was all along flat, straight parts of the highway. Reports were based upon the cars own fuel efficiency monitor. - 135 km/h 7.8l/100km (30 mpg) - 125 km/h 6.5l/100km (36 mpg) - 115 km/h 5.4l/100km (43 mpg) I never realised speed made such a difference! (Mpg is US gallons)
      • btilly 11y ago
        The reason why it matters is that air resistance is proportional to the square of your velocity. At high speeds that term dominates.
        • jtuente 11y ago
          Due to some physics things that I don't understand, it actually ends up proportional to the cube of your velocity. source: presentation by Dr. Rizzoni at Center for Automotive Research at OSU
          • semi-extrinsic 11y ago
            It's actually neither square nor cubed, but you can use those approximations with varying success for different car shapes and Reynolds numbers. There are several different physical effects that together create drag: you have form drag, skin drag, interference drag, and even lift-induced drag (the last one essentially only on sports cars).
          • mikeash 11y ago
            Power consumption is proportional to the cube. Aerodynamic drag i.e. force opposite the direction of travel is proportional to the square of your velocity. Power consumption for steady cruising is equal to drag multiplied by speed. Thus power consumption is proportional to the cube of speed.
            • btilly 11y ago
              Right. And if you're measuring miles per gallon, you're interested in energy consumed per mile traveled, not energy consumed per second. And aerodynamic drag tells you energy consumed per mile traveled thanks to the relationship that energy is force times distance.
      • protonfish 11y ago
        That's - 84.0 mph - 77.5 mph - 71.5 mph For us in the states.
        • deleted 11y ago
          [deleted]
        • bayesianhorse 11y ago
          No, for you in the states it's 70mph ;-)
      • brc 11y ago
        A dramatic demonstration of this is the Bugatti Veyron. Between the original version (1,001 hp) and the SuperSport version (1,184 hp) - the top speed only increased from 408 kmh to 431 kmh. So a 183 hp increase in power yields only a 23 kmh increase in top speed - bearing in mind that 183 hp is more than most passenger vehicles have in total. It gets exponentially harder to push air out of the way the higher the speed gets.
• tremon 11y ago
  This is by no means an exhaustive list, nor an authoritative one. Would love to hear other's thoughts on these: - When accelerating, try not to over-extend the throttle. If the engine is at 2k rpm, you get just as much acceleration from 30% throttle as 100%, at half the fuel cost. - Release the throttle well before you reach a traffic light/stop sign. Deceleration by engine will cause a smoother stop and gives the traffic light more time to turn green. You spend less fuel trying to reach the stop line, and spend less fuel accelerating again. Bonus points for shifting down while decelerating. - Keep tires well-inflated and oil levels up. Less friction means less wasted energy on both. - Choose the highest gear when cruising. Most cars since 1990 can do 50kmh (30mph) even in fifth gear, as long as you don't need to accelerate. - Drive slower. Most car engines are most efficient around 3500 rpm, which maps to somewhere between 90-110 kmh (60-70mph). Most highways allow for a higher speed. Diesel engines have their optimum at 2000 rpm, or so I've been told. Of course most of this works best with a stick shift. I've never driven an automatic.
  • userbinator 11y ago
    Choose the highest gear when cruising You can do this for automatics too - you just have to learn where the shift points are and drive at the right speed. Lift up on the accelerator quickly to upshift, press it down quickly to downshift. One thing that I notice easily when riding is when the driver is constantly staying at only a few km/h slower than the shift point, causing the engine to spin faster and consume more fuel than necessary. It often means the car is louder and vibrates more too, so not a good thing overall. This is harder to do for newer models with quieter engines and smoother shifts but older automatics have very noticeable shifts and engine noise to judge whether you're near the bottom or top of each gear. It's very noticeable in larger trucks and buses. Edit: another point I'll add to the list is traffic light phasing - look far ahead and observe the timing of the lights, and adjust your speed so that you're not going too fast (you'll arrive at a light before it turns green) or too slow (it'll turn red very shortly before you arrive). Obviously, you should do this only if traffic permits, but it's a great "trick" (not so much a weird one) when you can get from your origin to your destination at a constant speed with nearly no stops.
    • 11y ago