For their F-0’s AMT variant, what BYD did was bolt a Magneti Marelli kit onto the same 5-speed manual gearbox of the micro-hatchback’s MT variants. Like other carmakers in China (and also in India, by the way), BYD found that an automated manual transmission, an AMT, is a cost-effective way to, well, to automate most or some of the stickwork on a manual gearbox. It isn’t an automatic transmission built from the ground up, but rather a distinct module bolted onto a manual box, adding logic controllers and servos to work both the clutch and the gearshift.
There’s no clutch pedal to work with. All clutchwork is delegated to the electronic shifter, leaving just the brake and gas pedals. And, about that gas pedal, the AMT also overrides your throttle inputs as it works the clutch, letting up on the gas as it pulls back the clutch for a shift, then bringing the gas back to where you had it as it lets the clutch back in to engage the new gear.
It’s an entirely different experience compared to auto-shifts on a conventional AT where the fluid link of the torque converter allows shifting on the fly without any let up on the throttle, not even when stepping through gears in semi-auto mode. But it’s definitely a sequence that’s familiar to the stick savvy.
In forward drive, the F-0 AMT has three modes—A, S and M:
- A for full automatic operation, the gearbox taking care of all shifting from first to fifth. From the N (neutral) starting position, sliding the stick down will spring it into the very center of the selector, putting F-0 in A.
- S for a sportier sequence on the automatic shifting, the box keeping you in each particular gear longer, milking its torque advantage as you accelerate up. Clicking the S button while the F-0 is already in A puts it in sport mode. Clicking the button again toggles it back from S to A.
- M for a manual mode that let’s you roll out in 1st or 2nd (for driving off in snow conditions) and sequentially shift up or down through all five gears. Coming out of N or R (reverse) puts you A by default. But then after, even with the car already moving, flicking the stick left and letting it spring back to the center will toggle you into M, and flicking it again puts you back in A.
Showed up by software
When I had driven the MT variant last year on a real world mission, an outreach drive as usual but for a different publisher, I found the F-0 thoroughly enjoyable (see the story: The BYD F0, on the job). The wheelbase’s rectangle is relatively short and wide, the overhangs on the body are minimal both front and back, and those wheels set nearly at its corners make for a very responsive city car that’s sized just right for zipping around the metropolis.
So, I thought I found a way to both eat and have the proverbial cake by nailing down a shift sequence to run the peppy hatchback as efficiently as possible. Noting that the F-0’s 67hp 998cc engine spools up very quickly with its three cylinders, revving up easily from under 1000rpm to almost 4000rpm with just normal pressure on the gas pedal, I asserted that minding the revs and up-shifting at 3000rpm as the micro-hatch hits 20, 40, 60 and 70km/h to reach 5th gear, would put it in it’s best fuel-saving groove.
But, as it turns out, I was wrong. Working with the same gear ratios as on the manual box, that 3000rpm shift-point I had pegged is where the AMT would have you in its more aggressive S mode, with shifts happening at a similar 20, 40, 60 and 80km/h. In contrast, in normal A mode, the F-0’s AMT programming defaults to extreme economy, its logic and fast electronic controller managing to deliver an even more frugal shift sequence.
No sir, 2000 is better
In A, the automated gearbox emulates how an eco-run master would short-shift for optimal fuel savings. Normal, easy pressure on the gas pedal gets you to shift points as soon as revs hit 2000rpm: up to 2nd gear by the time you hit 15km/h, then up to 3rd by 25, to 4th by 45, and finally up to 5th gear by the time you hit 60km/h. Obviously a max-conserve regimen to get to the top overdrive gear quickly and even at a low 60km/h that’s arguably the highest speed at which you can occasionally cruise in city traffic.
At 2,000rpm with its fairly flat power curve, the F-0’s BYD 371QA engine already delivers 86% or 57lb-ft of its peak torque of 66lb-ft at 4000rpm. It really is enough for getting you to the next shift point. The problem is, with the throttle so responsive on the MT variant, that 2000rpm comes and goes very quickly—difficult to hit when you’re minding a stick. But with the drive-by-wire controllers on the AMT kit, triggering things at 2000 is just routine of course.
My best on the MT variant was 16km/l. On the F-0 AMT, with full credit going to Magneti Marelli engineers, I saw that number being nudged up to almost 18km/l.
Still a clutch in there
If you remember that an AMT still has a clutch to manage, then its operation becomes predictable. I’m saying that’s a good thing. If you’re an old stick guy, like many of us are, you’ll be looking out for when and how the AMT box will be easing off and pushing in the clutch while it does its autonomous thing with the gearshift.
On rolling out, shifting from N down to A will put the F-0 in gear only if you’re stepping on the brakes at the time. If you forget this and, perhaps, put it in A not while stepping on the brakes but rather with the parking brake engaged, it won’t put you in gear. The stick selector will be in the center position where it should be but the dash display will show you as being still in N. Remember this and don’t panic when you might be coming off the handbrake instead of the brake pedal (like when you move again in stop-and-go traffic). Simply step on the brakes, then cycle the stick to N then back to A. That’ll put you in gear.
Now, with the car in gear, the dash display showing that telltale A, you’ll notice no urging forward like what you’d feel on a conventional AT with its torque converter already engaged. Reason is that the AMT’s program will start easing in the clutch only when you take your foot off the brake. Quite natural really, like what you’d do on a manual transmission.
But you can still use that old handbrake trick when rolling out from an uphill hang. Just do what you’d normally do after shifting the selector in drive while stepping on the brake. Engage the handbrake, step off the brake pedal, and then give it a little gas in A before disengaging the handbrake as well.
Jerky only if you’re passive
As the car accelerates and cycles through its upshifts, the AMT will execute each one as you yourself would if you had full control of the clutch and the gearshift. When it hits a shift point, it’ll override your throttle control, idling down the engine to prevent it racing as it eases back on the clutch. Only with the engine idled and the clutch disengaged will it then actually change gears. Afterwards, it’ll reengage the clutch then give you back full control of the throttle. Keeping your foot pressed down on the gas pedal through this evolution will cause what critics have called that “jerky” AMT acceleration.
With a gear shift completed, the gearbox will restore full throttle control, putting the engine revs instantly back where your foot on the gas tells the AMT to put it. What’s this like? Have you seen the movie Apollo 13, particularly the part when their first stage booster cuts out and the second stage suddenly comes on to take over? It’s like that. You’d feel a sudden absence of acceleration as the AMT starts into a shift, followed half a second later by its equally sudden return. But, again, that’s only if you keep pressing on the gas pedal the same way throughout the gear change.
If you visualize what you’d be doing on a manual gearbox and fall back on muscle memory, you can rely on instinct to ease off the pedal as soon as you sense the engine idling down in preparation for a gear shift, imagine that familiar “one-one thousand” second’s count, and bring back the gas gradually when and instead of thinking “thousand.” (Remember? It takes just a half and not a whole second.)
Economical to a fault
Economy-focused A mode on the AMT won’t give in to impulsive sprints, keeping you in the current gear even as you suddenly push harder on the gas pedal. On conventional automatics, the common response is a downshift for multiplied torque as the RPM spike translates this into horsepower. Not so with the AMT, not in A and neither in S mode.
If you think about it, it really is better to keep the AMT in the same gear, even when you need some sudden acceleration. Remember that any shift triggers disengaging the clutch while idling down the engine. Imagine what this would imply when you suddenly need some powerful acceleration. The AMT will oblige, ironically, by first throttling down the engine for the half second it needs to complete a gear change. Nope, not an ideal scenario.
Somewhat related to this, A mode will keep you in a particular gear as long as it keeps you moving along at the gear’s corresponding minimum speed, regardless of not being able to accelerate beyond it. This makes for some hair-raising episodes when you’re going uphill. An A mode’s short-shifting sequence, while good enough on level ground, could cause a sudden loss of critical gear reduction as you deal with a climb. Instead of speeding through a climb on a lower gear, an untimely up shift would likely keep you at a low speed, not letting you accelerate further for the duration of the uphill run … makes for a lot of horn-honking at your back.
Now, to deal with these shortcomings of the AMT when compared to conventional AT’s, it might’ve crossed your mind to keep it in S mode full-time. But notice that while this may pre-empt any problems in uphill climbs, it doesn’t really give you the the downshift option for those occasions when you need a burst of acceleration, occasions like on overtakes to get out from behind slower vehicles. So, I’d suggest going back to basics, going to M mode instead. Do a quick left flick on the selector to put the AMT in manual M mode, then a quick down flick to downshift.
Best practices using an AMT’s best programming
Notice how many times I went into the benefits of M above those of other modes? There’s the bit where I mention going with M to sidestep acceleration jerkiness. And there’s the part just above where I suggest M mode as being the answer for the AMT’s acceleration shortfalls. Admittedly, I started out thinking it’s best to just keep it in M, commanding the gear changes myself while still enjoying the break from having to work a clutch pedal.
But in the end, after logging about 250km on the F-0, I’d suggest keeping it in A mode instead. Just build on old muscle memory to learn a new set of instincts for easing off the gas pedal when the gearbox idles down the throttle and come back in with the gas only after it completes a gear change. This way, you reap all the fuel-saving benefits of the AMT while enjoying its clutchless operation. Consume less fuel than with a conventional AT while still enjoying its clutch automation, what’s not to like?
Stay in A, but be ready to flick things into M real quick. When you need powerful acceleration, instead of finger-hunting for the S switch, better to then finally go into M mode with an easy, sightless left flick on the big selector stick, followed by equally natural down flicks, and some subsequent up flicks, before again settling down to a cruise back in A with another, final left flick.
So, there it is: stay in A but still with a suggestion to at least use M occasionally. Why? It’s fun, for one, and it comes with the challenge to sharpen your stick skills even more. In M mode, you can pop out of gear and into neutral while rolling, sure, but you can’t get back into gear without coming to a full stop and keeping your foot on the brake. So you lose that old crutch of being able to coast along while you’re uncertain what gear you should be in. And this is good. A professional driving and race instructor, two of them actually, kept drilling me on the wisdom of staying in gear all the time. Driving the AMT in M mode, the absence of a clutch pedal being fortunate in more ways than one, trains you up to do just that.