So I'm learning to drive my manual civic and I'm getting some mixed tips on how to slow/stop to save gas and clutch. The 4 different ways I've been told are:

1. put gear in neutral and let car cruise until stop and break
2. slow down with the break until you're almost stopping, then clutch and put in neutral
3. down shift each gear until stop
4. engine break (don't exactly understand this one yet)

I've read that putting gear in neutral and let it cruise will save gas (is that true?) while other ppl say cruising in neutral uses more gas than just breaking while in gear... slightly confused.

any feedback will be helpful, thanks

 

3 and 4 are essentially the same thing. If you notice, when you're in a low gear (ei, 1/2/3) without being on the gas nor the brakes, the car slows down faster than it does in a higher gear (ie, 4/5). Without getting too deep into it, it has to do with gear ratios. Engine braking is basically using that trait of the transmission to help slow the car down.


As for me, I downshift and brake (heel-toe shifts) until I'm at around 2k rpm in 3rd; after that I just throw it in neutral (my mustang has been geared; better acceleration, but 2nd feels like 1st gear in most cars lol).

For the gas savings, it really depends. New-ish cars have programming that shuts the injectors off while the car is in gear under 0% throttle, meaning more gas savings than throwing it in neutral; basically, the only time you'd be using fuel in a car that does that would be when you "blip" the throttle to rev-match. Most older cars do keep the injectors on, even at 0% throttle, in which case pressing the clutch in or pulling it out of gear would net fuel savings.

 

number 2 and 4 are the same, and that is what you should do. when you stay in gear without clutching, your engine will be slowing down the car and this is called engine breaking. popping into neutral will waste gas since your car needs to pump in fuel to maintain idle. on the other hand, when you're off the throttle and still in gear, the ecu will see that you are 0% throttle and the engine is not dying so it will pump no gas at all into the engine, thus saving gas.

and i gaurantee you will save gas, my buddy in a 96 hatch was consistently getting 39 mpg and he told he simply couldn't break 40mpg. i asked and he said he would go into neutral so i made him change his driving habit and he immediately got 43 mpg.

the s2k isn't that great on gas but i consistently get 33 mpg driving with this method

 

Braking while in gear is correct. When you are not pressing the gas pedal and the motion of the car is making the engine turn faster than idle speed, it uses no gas. If it is in neutral it needs to burn gas to keep idling. Stay in the same gear you were cruising in and apply the brakes. When the speed reaches about 15 mph, press in the clutch and shift to neutral.

Downshifting through all the gears is a lot of wear on the clutch and transmission. These parts are much more expensive to replace than the brakes are. Thus it is bad practice to do except in emergencies where the brakes don't work.

Engine braking is using a lower gear while descending a long steep hill on the highway, one where the car would gain speed out of control if you didn't use the brakes on the way down. You downshift once at the top and let the friction of the engine keep the car from speeding up so you don't need to use the brakes as much.

 

i would not downshift, in order to make the car decelerate smooth then you will need to revmatch and blip the throttle everytime you do, thus wasting gas

oh, and you should decelerate in gear until about 1000rpm, this way you don't have pay attention to the different speeds you need to clutch in at for different gears

 

I'm just going to throw this out there: a proper heel-toe downshift will have almost no slip between the flywheel and clutch. Done properly, your clutch will last just as long as if you hadn't downshifted, but you'll still have the added deceleration of higher gear ratios. At low speeds (~30mph and slower) I'll just throw it in neutral, but if I'm going 55mph and a light turns yellow, you better believe I'm going to be rowing back down through the gears.

And I'd argue it doesn't wear the transmission any more than simply driving the car will. The clutch, possibly (like I stated, it depends on your shifting ability), but to wear the transmission down, I'd think you'd have to be pretty bad at driving. I'd also like to see the total cost of replacing the brakes over the lifetime of a transmission vs. the cost of a used transmission (which can be had for a D-series for less than the cost of two OEM rotors).

Just some food for thought.

*edit: @tbp: do you realize how little gas you're using to raise the engine speed ~500rpm? And I don't know about you, but I spend more time looking at the road than the tach; unless I'm running it to redline, I'm going to go solely off the feel and sound of the car.

 

It might not save fuel, but heel toeing is a lot of fun

 

yes, the clutch should be perfectly fine, but the syncros are still stressed everytime, unless you're double-clutching heel-toe downshifting

 

yes, but when you're going for absolute best gas mileage, which i enjoy doing for fun for daily driving, every last bit of gas counts lol. my personal record for the s2k was 36mpg, which i'm proud of. for my hatch was only 39, but i have a bad fuel injector.

and yes, i also solely rely on sound and vibration emitted to me through the car, but i'm sure the new driver op is not able to do this lol

 

Ahh, missed the part where he said he's learning to drive it.

I'd argue that, yes, it's undue wear and tear on the synchros, but no more wear than any other shift would be. Realistically, the extra shifting isn't going to cause them to fail any earlier. If you really want to talk synchro damage, let's talk about grinding gears


And since the OP is new to driving manual transmissions, I'm going to clear this up since he's probably confused:

a heel-toe shift would be when you brake and downshift at the same time. The toes on your right foot are pressing the brake pedal down, and while clutching, you swing your heel up and tap the gas pedal to raise the engine speed up enough to smoothly downshift. It's used during racing to maintain traction entering/during a turn, since a rough, abrupt downshift could push the tires outside their friction envelope. On the street, it's mainly used for a smoother downshift while braking (unless you're doing some "spirited driving", in which case it's used for the same thing as racing).


(and as a side note, 36 in an AP1/AP2 isn't too shabby. I've seen 31.5 in the mustang, which I think is pretty darn good for a modified mustang )