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Does engine braking instead using the brakes help save fuel? I'm never sure...Also, sometimes I see signs around the city saying "no engine braking" does that mean it's illegal?

My second question is does braking use gas? I would think that the car gets the power to stop the brakes from the gas...in that case I guess engine braking would help fuel consumption...

Any ideas?

The act of braking does not consume fuel however, all of the energy used to get the car moving is lost when you brake. So when you brake you lose energy so you have to get it back by burning fuel. Hope that helps.

I think it's illegal because it might violate some type of noise ordinance. If I engage in some engine braking when I'm at too fast a speed, it might shoot up to 3000 RPM or higher and that makes quite a bit of noise.

Be mindful of any drivers to your rear when engine braking. Flash the brake lights with a tap so your deceleration intent is visible. Engine braking saves brake wear. It also means you accelerated more than was required to reach the approaching stop.

Any braking (engine or friction), expends momentum which must be repurchased by burning fuel. Braking remains preferable to hitting an object in front of you.

From the bicycle world: "Brakes just slow you down."

Best thing is to coast to a stop, or at least down to 10-20 mph.

Generally speaking, Braking is Braking whether your using brakes, engine, or anything else to slow the car, your hurting your mileage.
IF your car will do DFCO then engine breaking will not hurt your mileage as much as brakes. But even DFCO will not help like coasting.

The sign's for No Engine Brake are there for Noise. Trucks often install a Jake Break (http://www.jakebrake.com/), the Jake Brake enhances engine braking. Jake Brakes control the engins Valves causing the engine to act like a compressor adding resistance and slowing down the truck. You will often hear this as a truck get loud as they slow.

Also, sometimes I see signs around the city saying "no engine braking" does that mean it's illegal?

Those signs refer to a big rig engine brake system.

You ever here them slowing down and making this big loud farting sound? That's the sound those brakes make.

My mom, a truck driver, used to chide them all the time for using them. It's just not needed if you keep your eyes far enough down the road.

She wasn't a hypermiler, but she pass on a lot of FE tricks to her kids.

Yep, the "engine braking prohibited" signs refer to the compression/exhaust brakes installed on big rigs, NOT engine braking with an ordinary automobile.

Here's the deal:

If you're going to resume acceleration at the end of your coast (i.e., you're trying to maintain forward momentum and NOT trying to burn off speed), coast in NEUTRAL. You'll still use fuel idling your engine, but you will hold your momentum better and ultimately waste less energy than you would by coasting in gear.
If you need to slow down, hold speed on a grade or come to a stop -- in other words, if you'd otherwise be on the brakes ANYWAY -- then it's better to coast down IN gear. On most cars made in the last 10-15 years this activates Deceleration Fuel Cutoff (DFCO), which causes your engine to burn NO fuel while you're coasting. Since the vehicle's momentum keeps the engine spinning, no fuel is needed to idle it. On most DFCO arrangements, the idle fuel flow kicks in again instantly as rpms drop down to somewhere in the 1100-1500 rpm range, and it's so instantaneous and seamless that the vast majority of drivers are unaware of it.


My greatest use of neutral coasting was coming off the shoulder of Mt. St. Helens last spring. I started a coast at 4000 elevation and went 11 miles without touching the gas. You can bet that if the car had been in gear, I'd have been on the gas a few times -- using a lot more than the couple ounces of gas needed to idle 11 miles down the hill.

My greatest use of coasting in gear (DFCO) was near Boise last summer. We drove up to Bogus Basin ski area, about 4500' above the city. The grade coming back into town was steep enough to require braking, so I put it in gear for a fuel-free DFCO almost the entire 18 miles back into town. Not only that, but the grade was steep enough to maintain momentum with the car in gear and the A/C on -- which meant cool air inside on that 95 degree day without burning an extra drop of fuel.

A similar situation to your downhill run (for me, up in Duluth) is what convinced me that the Elantra does not have DFCO. I should have seen a significant bump in fuel economy for that tank but there was nothing.