Aggressive driving speeding, rapid acceleration and braking wastes gas. Driver feedback devices can help you drive more efficiently. While each vehicle reaches its optimal fuel economy at a different speed or range of speeds , gas mileage usually decreases rapidly at speeds above 50 mph. I usually drive 80 75 70 65 60 55 mph on the highway. At higher speeds, the estimated price per gallon is increased based on the additional fuel you use by driving faster.
The price of fuel doesn't actually go up, but this is a useful way to put the cost of driving faster in context. Save Money: This graph shows how much money you can save by slowing down. Cost per gallon and cost per miles show the difference in cost at your typical highway speed and the cost at the reduced speed. Savings per extra time incurred is calculated as the money saved by slowing down divided by the extra time incurred:.
Speed-mpg relationships are based on dynamometer tests of 74 light-duty vehicles representing a variety of manufacturers, nine vehicle classes, engine sizes 1. Almost all are conventional gasoline-powered vehicles. Only one diesel and two hybrids are included; no plug-in hybrids or electric vehicles were tested. These estimates work best for well-maintained modern gasoline light-duty vehicles and will likely be less accurate for diesels, hybrids, and vehicles with cylinder deactivation.
Their applicability to plug-in hybrids and electric vehicles is unknown. Therefore, our cost and savings estimates should be conservative. If you need to use an external cargo container, removing it when it's not in use will save fuel and money. Avoid keeping unnecessary items in your vehicle, especially heavy ones. Idling can use a quarter to a half gallon of fuel per hour, depending on engine size and air conditioner AC use.
Turn off your engine when your vehicle is parked. It only takes about 10 seconds worth of fuel to restart your vehicle. Turning your engine off when your vehicle is parked can save you money. Here are some tips to help you maximize your savings. MPG in top gear. It's an interesting shape that reveals a lot about the car that made it: Source The benefit of electric assist is obvious up to around 42 mph, at which point the engine spins up, mileage abruptly falls off a short cliff, and then continues to decrease more gradually as speed rises.
Source Here's another with a bit more information about where it came from - a Volkswagen Golf GTI though conditions are unknown : Source High speed mpg They ran a number of cars at much higher autobahn speeds - between 50 and mph on a test track while recording fuel consumption: Source The Blackfly graph: MPG vs.
The company says 44 mpg US highway, 37 city. Some drivers are already beating that in various economy driving contests. An efficient engine, very light weight and aerodynamic design. Cheapest to own? That makes it one of the cheapest cars to own. And its hp, 1. Latest 10 posts: 1.
Recipe for getting Snapshot: effect of tire pressure on rolling resistance 4. Metro mania: forget stocks, put your money in old Geos! Experiment: how long should a block heater be plugged in? Project Convertible XFi: alfresco efficiency The floor is yours: MetroMPG opens a fuel efficiency forum Show all posts. Save fuel with a ScanGauge II fuel economy computer. In the above expression, the energy is in units of Joules. However, the more energy you use, the more gasoline you need.
The amount of energy is proportional to the amount of gas. Where the constant K contains both unit conversions and an efficiency of the engine. I know the change in energy for the car from above. Let me introduce a new constant B to represent all the stuff in front of the velocity squared term in the air resistance. Now let me make an assumption. What if the frictional force is much less than the air resistance force? Maybe this isn't such a bad approximation - especially at highway speeds.
This means that I can write:. What next? Well, let's take an average car. Suppose this is a pretty nice car and gets 30 mpg at 70 mph. Using these values, I get:. Now what about the second car? If it has a speed of 85 mph, what would its fuel efficiency be? Oh wait, if the speed limit were 85 mph people would really drive 90 mph. This would make a fuel efficiency of 30 mpg at 70 mph go to 18 mpg. Notice that in the manner I calculated the efficiency, it doesn't matter what units you use for the speed as long as both speed have the same units.
One more calculation. What if you have a huge SUV that gets 18 mpg at 70 mph? You would only get 12 mpg at 85 mpg.
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