Idling a car?

Question

Just a few general questions about idling. I know that no answer will be the exact same for two separate cars, but I can at least use a ballpark reference if anybody can offer it. The car I'm driving is a 1998 Nissan 200SX.

Compared to when I'm driving at say about 45mph, how much LESS gas am I using when I'm idling with the engine running? Is the difference significant? How about compared to the initial ignition of the engine?

What if I don't have the engine on and I'm just sitting there listening to the radio? Does that eat up the battery? By how much? Should I not do it for too long? How long is too long?

Answer 1

If you will be stopped more than a minute the engine should be cut off.

The best speed for fuel economy is between 45 and 55 depending on the gearing. You want to be locked in top gear for best mileage.

The radio in most cars today uses very little power so you can listen until you grow old. If you will be parking the vehicle for an extended period of time, disconnect the negative side of the battery.

Drag Increases with the Square of the Wind Speed
Both lift and drag increase with the square of the wind speed.
The reason why drag is much more of a problem for a racing bicyclist than for, say, a runner, is that a fast runner will be moving at speed of some 6 m/s (21 km/h, 13 mph), whereas a racing bicyclist is moving at a speed of some 12 m/s (42 km/h, 26 mph).
A modern car (drag coefficient 0.34) with a 110 kW (150 HP) engine will be using about 4.6 kW (6 HP) of power to overcome air drag and 11 kW (14 HP) for mechanical propulsion (rolling resistance etc.) when it is being driven at a constant 80 km/h (22.2 m/s, 49 mph). When driving at its top speed of 210 km/h (58 m/s, 128 mph) it will be using 82 kW (112 HP) to overcome drag and the remaining 28 kW (38 HP) to overcome rolling resistance etc.

Answer 2

There is a fair amount of difference in gas usuage whether you are just idling or running down the road at 45mph. I don't have an actual figure for you, but you are using a lot less idling. You would even use less if you turned the engine off.

The battery will run down if you leave the radio on. The radios of the modern era, don't use a lot unless you have a bunch of amps and subwoofers attached. A stock radio system should be able to play for a couple of hours and not give you any problems. Assuming that the battery is in good condition. good luck.

Answer 3

Here's what the car manufacturers reveal:

Maximum performance for most cars is between 35-45 MPH.
This means, safety, shocks, struts, springs, sway bars, tires, and miles per gallon or the whole drivetrain.

When you are idling you are getting Zero MPG's. And your not producing air flow through the radiator and A/C condensor coil or other coolers in the front of the engine. The heat in the engine compartment will not escape and make everything else run very hot, hoese, belts, springs, sensors, and so on.

The alternator likes cooler temp's as well and excess heat will wear the bearings faster as well as other heat sensitive components.

Good Luck!