The general rule of thumb (excepting situations like hills) is you brake to slow down, you downshift to speed up. In other words, if you’re going into a curve at 60 in 5th and need to slow down to 20 to make the turn, you use your brakes to slow down from 60 to 20 (entering the turn) and downshift to 2nd (heel-toe double declutch for maximum performance) so you’re in the gear best suited for good acceleration at that speed. You don’t use any engine braking from the 5-2 shift. You use that change in gears solely for the speeding up. At least that’s how I’ve been schooled.
Thanks for the responses. I’m going to pase a followup question that hasn’t been answered yet:
Just curious, but how does the average schmuck downshift? Do they use that method, or simply release the clutch slowly, as I mentioned in the OP?
I ask because I hadn’t really heard of the “matching RPMs” method until I researched it. Is it something most manuel drivers know?
I’d say most people just let out the clutch. In the US, the vast majority of people own, and learn to drive on, automatics, so manual shifting is rarely taught in drivers’ ed. If they have to learn it, most just pick it up from friends or family members. (Which is probably where they learn the bad habit of downshifting instead of braking.)
I teach race-style driving on a racetrack, and most of the new students I see don’t know how to do heel-toe downshifting, although some have heard about it.
So I’d say that only a very small minority of all manual transmission drivers (who constitute a minority of all US drivers) actually practice heel-toe and/or double-clutching. And, as I said before, it’s important on the track, when you’re trying to prepare to accelerate while braking, but it’s not terribly useful in most street situations. I do it all the time on track, but almost never on the street.
Probably not anymore. Before the days of the synchromesh, you had to double declutch. With modern manual transmissions, you don’t. Sure, you save some wear and tear but, really, it’s not necessary. I think only a small minority (under 10%) of manual drivers bother. I think if you’re smooth and gentle with all your gear changes, the amount of wear and tear you’ll save with double declutching on a modern manual transmission is fairly trivial. But someone may correct me if I’m wrong.
What’s double declutching? I know how to drive a stick, i.e., a modern stick from 1965 (my first Beetle) and onward…
Explained in detail post #7 this thread. AKA “double clutching”
IIRC, double downshifting involves taking a vehicle out of gear and into neutral, then with the clutch pedal released blipping the accelerator, then putting the vehicle back into the lower gear.
That’s not allowed during your driving test in the UK, possibly a way to fail immediately.
It means you have lack of control over your vehicle, say for example in the odd event you may have to power out of the way of another vehicle about to run into you from behind in a queue of traffic.
I usually give the accelerator the briefest blip as I push the clutch pedal all the way in and then let the pedal out again, no double clutching. Is this as good as fully double declutching?
Dropping down gears simply to stop is inappropriate - at least that was what I was taught (1998). The brakes do the job better than anything else, so keep your hands on the wheel to deal with anything you weren’t expecting.
Obligatory link to the Straight Dope Mailbag article on “Jake Brakes”:
http://www.straightdope.com/mailbag/mjake.html
10-second summary: Most large trucks are equipped with “engine brakes” that increase engine compression specifically to slow the truck down.