tbirdjayc, asked a good question but Todd is right, the amount of missinformation being posted as fact makes the mind spin. Some have posted good accurate advice but others seem to be pulling ideas out of thin air.
Also it should be noted that there is a considerable difference in wear & tear and vehicle dynamics/stability between mild/moderate downshifts and downshifting to decelerate at a stopping rate to reduce brake wear. The difference is in the degree of deceleration.
First, take absolutely no offense by this tbirdjayc, but simply because your father or my father has been involved in something or doing something for a long time doesn't make it right or wrong. Also their knowledge comes from RWD not FWD and the dynamics are different.
Downshifting is fine but it
DOES NOT slow you down quicker or burn more fuel.
The easiest one first - You burn less fuel by down shifting as you reduce speed then by going to neutral (I'm talking about mild downshifting to the gear below what you would normally be in to cruise at your current speed). The ECU is smart enough to know that there is no throttle and the revs are above 1,000 (no threat of stalling), so it will shut off fuel delivery. I'm not sure when manufacturers started doing this but my fading memory seems to recall that it was approx. 20 years ago with the advent of ECU controlled fuel injection and pioneered by BMW. My Volvo has a trip computer that displays instaneous fuel consumption and it is very clear to demonstrate with that. My Lincoln Mark VIII LSC that I traded in on the Volvo had the same type of display and gave the same feedback.
The MTX5 and Duratec are as capable as most any other vehicle in putting up with the strain of downshifting, the question is, what is gained by introducing this strain. I'm referring to downshifting at anything more than mild.
1 - Road Racers DO NOT downshift to slow the vehicle down. They do so to a) stabalize the car for when the brakes are let off and b) to be in the correct gear for accelerating out of a corner. Idealy, a perfect downshift in a racing situation would see
NO deceleration as that would unsettle the car and,
ALL deceleration is done by the brakes so that the car is as balanced as best possible on all four tire contact patches, or in special circumstances on the one or two contact patches desired (I've rarely come close to the ideal).
A FWD already has more weight than optimal on the front wheels and engine braking only makes things worse. It can destabalize a vehicle enough to make it spin, under extreme conditions, if you turn (even just slightly) during the process. Therefore in an emergency situation you should only downshift if you need to accelerate faster than the gear you are in will allow.
2 - Wear & Tear. It's already been noted correctly that brake pads are considerably less expensive than engine/clutch/trans parts. It's not that any of these are going to fail, it's simply a matter of which is less expensive to replace due to wear and which should be considered a normal replacement item. Engine braking places a force on the pistons, rods, crank, bearings etc., this has a wear factor. The more one does it and the more agressivelly it is done, the greater that wear. Not likely to kill your motor but just like athletes an NFL players career is usually shorter than an baseball player's even though the MLB plays alot more games per year.
3 - Brake failure. This should only occur if your brakes have not been properly maintained. If a persons brakes aren't properly maintained then it's likely the motor isn't either. Again, we are talking about degrees. Selecting a slightly lower gear on steep declines to stop the vehicles speed from increasing is accepted wisdom, using lower gears in those situations to decelerate the car at anything more than a relaxed rate is considered ill-founded, questionable at best. The brakes on the SVT are designed to generate a stopping power in excess of 800 whp - it would take 800+whp to overcome the SVT brakes!
4 - The idea of never coming to a stop with the car in neutral has more to do with the greater possiblity of cars in the past stalling than reduced reaction times, etc. but both have valid points. Again it really is a matter of degree. In everyday driving with very little congestion, we often drive less alertly then in heavy traffic (one hand on the wheel, etc., etc., etc.).
tbirdjayc, it's more a matter of degree than absolutes. The absolute best braking possible is in fact with the vehicle in neutral, but that is only in a static or unique situation (downhill snow/ice, etc.). Once you introduce the variables of the real world then things become a little more grey vs black and white. You want to be in a lower gear if you need to accelerate but not for significantly slowing the car. If you're aware of your surroundings it may well be apparent that there won't be any need to accelerate and just using the brakes with the tranny in neutral would be fine. One should have the tranny in neutral when sitting at a light to save wear & tear on the clutch and put it in gear just before the light vhanges.
In Europe, where the majority of cars are manual transmissions, many cities have the Amber traffic light come on just before the RED switches to Green. This gives a person sufficient time to put the car in gear just before the green light, a great idea. That and the Autobaun are two of my many
favourite reasons for driving there.
Regards, Alan
