Myth-Busting: Coasting in neutral can save you fuel?
Coasting in Neutral is claimed to save you fuel but does it? And, should you rest your hand on a manual gear shifter?
AH, THE INTERNET. It and your best friend’s cousin’s dad are filled to the brim with information that sounds pretty good but is actually rubbish. Like some of the other myths we’ve covered, on the surface it sounds like there could be a little bit of truth in slotting neutral when you’re travelling downhill, taking the strain off the engine and letting momentum do its thing.
And the idea probably comes from bike riders. I’m not sure about you, but whenever I rode down a hill on my bike I used the hill as a chance to take a rest, because I’d just had to ride up the hill. Not pedalling and letting the bike roll down was like being rocket propelled. Unfortunately, it doesn’t work like this for vehicles.
See, when you take either your manual or automatic out of gear and into Neutral when driving down a hill you end up using, at the minimum, the same amount of fuel and perhaps more because the engine is still working and the fuel is still flowing. So the argument that you’ll save fuel doesn’t work, because you won’t. See, many modern vehicles will, when the system detects the vehicle is coasting (no load being applied via the throttle), shut off fuel supply or in those with the technology deactivate cylinders to reduce the amount of fuel being consumed. Thus, coasting in gear will in 99.9% of cases use less fuel than when you slot Neutral and try and rely on momentum.
Another issue with slotting Neutral is that you’ll have no ability to accelerate because you’re not in gear, all you’ll be able to do is slow down via the brakes and this lack of control will mean, potentially, you won’t be able to avoid a hazard.
One of the biggest issues of all, especially for an automatic transmission, is to shift from Neutral into Drive while travelling at speed. Basically, you’ll be slamming gears and bands together, and while it’s likely you’ll only damage some inexpensive parts inside the transmission it’ll cost a bomb to get to those parts. It’s the same for a manual transmission, only the meshing forces are different because you could slot top gear, whereas the automatic will go straight into first gear from Neutral.
So, don’t coast down a hill in Neutral in either a manual or automatic transmission, you won’t save fuel and you could break your transmission when you move from Neutral to a Gear, oh, and you won’t have any way of accelerating when you’re in Neutral, so your vehicle control is greatly reduced. More than that, it’s illegal to ‘clutch coast’ in all States and Territories in Australia; it’s considered “not maintaining control of the vehicle” and will cause an instant fail on your driving test and more if you have an accident and it’s revealed you were coasting in Neutral.
What about resting your hand on the gear shifter. This one relates to manual transmissions. From time to time we’ve all been guilty of using the shifter as a hand rest, whether you’ve lingered on the shifter between gear shifts, or are just hanging your hand on it in the same way someone might fat arm on the window sill.
This is not really a myth that needs busting, more a bad practice that can bugger your manual transmission, but given there was a tenuous link to clutch coasting we thought we’d mention it.
Besides reducing your car control (you should always be driving with two hands on the wheel) resting your hand on the shifter between gear shifts can result in premature wear of the transaxle shift forks. Basically, connected to the shift lever are forks which push a collar to engage a gear; by resting your hand on the shifter you could be applying ‘an amount’ of pressure to the forks that are thus being pushed slightly against the collars in the transmission, causing premature wear of the forks.
Short story, don’t rest your hand on the shifter because you could cause wear inside the transmission.