Cordless screwdriver

Cordless screwdrivers drive small screws on your car without overtightening

What is a cordless screwdriver? A compact inline screwdriver with a bit holder and limited, adjustable torque for small screws. On a car it removes and refits number plates, trim panels and interior trim without stripping plastic threads. Drilling, wheel bolts and seized fasteners are not its job.

Cordless screwdrivers are compact, stick-shaped power screwdrivers that do one thing only: drive screws. Instead of a drill chuck there's a bit holder at the front, and a torque clutch limits how hard the screw gets tightened. In detailing it's part of the prep before the actual work: taking off number plates, loosening trim panels, removing interior trim. What that means for you: the screw comes out and goes back in, and the plastic behind it stays intact.

• Seven settings instead of a feel in your wrist. The FLEX "SD 7-320 4" cordless screwdriver limits torque in seven settings plus a max mode to no more than 5 Nm. Once the set level is reached, the clutch slips and stops turning. You set the force limit before you start, not at the moment you tighten.
• 3 Nm for a number plate holder. That's the tightening torque Tesla gives for the number plate holder in the Model 3 service documentation. It's an example value for one vehicle, not a standard for all. It shows the order of magnitude: small screws on a car need little force, and extra force tends to do damage there.
• 1/4-inch holder and 307 g weight. The hex socket takes standard bits, and a locking sleeve holds them in place. At just over 300 g the tool is light enough in the hand that you can go in straight in the footwell, at the centre console or overhead.

Detailing1's tip from the shop: Start every new fastener on the lowest torque setting and only go up a step if the clutch slips before the screw head seats. The F.A.Z. found that on large cordless combi drills, even the lowest setting still sinks a small 3 × 15 mm screw. Only change the setting when the tool is at a standstill, as FLEX specifies. Once you've found it, it holds for the whole row of screws on that panel.

A cordless screwdriver only drives screws, but with fine control

An inline screwdriver is a stick-shaped power screwdriver with a bit holder and limited torque, built for small screws that seat with little force and get damaged by too much. That's how Bosch describes the category: no drill chuck, but a bit holder and a clutch that caps the tightening torque.

Torque is the turning force on the screw, given in newton metres (Nm). The torque clutch works like a breaking point that never breaks: it disconnects the drive as soon as the set force is reached. In practice, that means you choose the force beforehand instead of guessing it while tightening. A tool with a low upper limit also has far less reserve to overtighten a small fastener than a big drill driver.

On a car, these are the small fasteners that get in the way of a thorough detail. Number plates and their holders, trim on door cards and the centre console, covers in the boot, sill trims. If you want to clean the interior properly, you take parts like these off instead of working round them with a brush and cloth. You'll find the right care products in the interior section.

The same principle applies outside. With the number plate off, the paint behind it is free for washing, polishing and sealing, instead of you working round holders and screw heads. The dirt line that builds up along those edges only disappears once the edge is exposed. The screwdriver isn't a care tool; it gives you the access the care needs.

In shops these tools are sold as stick screwdrivers, mini cordless screwdrivers or cordless inline screwdrivers. They all mean the same thing: a tool that drives screws in and out and nothing else. That very limitation is what makes it valuable on delicate parts, because every function it lacks can't put force in the wrong place either.

Inline screwdrivers, drill drivers and impact drivers solve three different jobs

Inline screwdrivers, drill drivers and impact drivers differ in how much force they deliver and how finely you can limit it, and therefore in which fastener they suit.

The drill driver, usually just called a cordless drill, has a chuck and two gears, according to Stiftung Warentest. In 2025 the German consumer testing body tested 18 V class tools, a completely different power league from an inline screwdriver. You use one to drill holes and drive long screws into wood. Its torque settings are designed for exactly that work and are correspondingly coarse.

The impact driver works with blows in the direction of rotation and delivers very high forces. It belongs on wheel bolts and rusted fasteners, never on interior trim. Wheel bolts get tightened with a torque wrench to the manufacturer's spec anyway; you'll find the value in your vehicle's owner's manual.

Then there's the shape. Drill drivers and impact drivers have a pistol grip with the battery at the bottom; the inline screwdriver is a straight stick. In the footwell, behind the steering column or between seat and centre console, that's the difference between going in straight and pushing at an angle. At an angle the bit slips more easily, and that's exactly where the surfaces are on which a scratch will show later.

The table shows why a bigger tool isn't a better choice for small screws. On a trim panel, more reserve means more risk, not more safety.

The torque setting mainly protects the trim

Too much tightening torque can strip the thread in the screw boss of plastic parts or push the trim panel in, so the torque setting limits damage to the part first and to the screw second.

Würth and assembly-tool maker Desoutter describe plastic joints as particularly sensitive to excessive tightening torque. The reason lies in the material: the thread is formed in soft plastic, which gives under load instead of resisting. Bosch adds that overtightened screws lose their clamping force. Day to day you notice it on the trim: it sits loose and rattles afterwards, even though the screw is in.

That's why other specs count when you choose one than with a big cordless drill. What matters are several finely graded torque settings, a low maximum, forward and reverse, a light for dark footwells and a bit holder that grips standard bits securely. Speed plays a minor role, because short screws seat after a few turns anyway.

A second question is the battery. Some compact inline screwdrivers have a built-in battery and charge via cable; larger tools run on an interchangeable battery platform. Built-in means no battery swap mid-job, but also no buying into a battery system. For occasional disassembly that's enough; if you already use a platform, check its screwdriver line-up first.

One value no tool maker can give across the board is the right torque for your screw. Vehicle manufacturers sometimes list it in their service documentation, so it's worth a look there before the first removal. Where there's no value, feel your way up as described in the tip above. It costs a little time on the first part and saves you a stripped boss.

The right bit protects the trim from scratches

A slipping bit is the second risk on trim besides too much torque, because it jumps out of the screw head and drags a line through paint or plastic.

Wiha calls this pushing-out the cam-out effect: as you tighten, the shape of the screw recess pushes the bit up and out of the head. Wera explains that Pozidriv bits (PZ) slip less often than Phillips bits (PH), and Torx transfers the torque even more securely. So check the recess in the screw head before you start, because PH and PZ look almost identical.

Clips are not a job for the screwdriver. Where trim also hangs on plastic clips, release them with a plastic trim tool. Lever there with a screwdriver blade or a bit and you'll leave dents right on the edges everyone sees later. Sort the screws themselves by where they came from, because they can differ in length and head shape.

When refitting into plastic, start the screw by hand and turn it briefly anticlockwise until you feel it drop into the existing thread. Only then does the screwdriver take over. That way the screw runs in the old thread instead of cutting a new one next to it, and the boss still holds the next time you take it apart.

The first panel on a new vehicle takes longer than you think. You hunt for hidden screws under cover caps, don't find the clips straight away and try out the torque setting. That's part of it. From the second side on you know the order and the setting, and removal becomes a routine that no longer holds you up.

The FLEX SD 7-320 4 stands for the compact class

The FLEX "SD 7-320 4" cordless screwdriver runs on 4 V with a built-in 2.0 Ah lithium-ion battery, seven torque settings plus max mode and a maximum of 5 Nm in a hard joint.

A hard joint means the screw meets solid material abruptly, metal on metal for example. For that, FLEX states 5 Nm. For a soft joint, where the screw pulls gradually into yielding material, the data sheet and the manual disagree, so we don't give a value here. No-load speed is 320 rpm, plus forward and reverse and an LED light with afterglow.

It charges via USB-C; according to the manual, the battery is full after about three hours. There's no power adapter in the box, but the USB-C cable and a bag are included. The bits supplied are one slotted and one cross-head bit. For Torx screws you need a separate bit set with a 1/4-inch hex.

FLEX doesn't publish the torque at the individual intermediate settings. That makes the settings a tool for feeling your way, not a measuring instrument. If a screw has to be tightened to an exact value, the torque wrench remains the right tool.

Two points belong in an honest assessment. The battery is built in, so the SD 7-320 4 isn't part of the interchangeable battery platforms we explain under battery systems. And FLEX lists control cabinet assembly, maintenance and furniture assembly as uses, not vehicle work. Using it on trim and number plates is our own assessment based on the specs, not a manufacturer approval.

One number plate a year doesn't need a second screwdriver

To undo a few screws, the cordless drill you already own in reverse will do; a cordless screwdriver only pays off with lots of small screws on tightly packed interior parts.

Nothing can be overtightened when you undo a screw; the risk lies only in tightening. So if you only take your number plate off twice a year, don't buy another tool. Back the screws out with your existing drill driver in reverse and refit them by hand with a matching screwdriver. That way the force when tightening stays where you can feel it.

If you regularly strip down interiors, remove sill trims or take off panels for cleaning, the compact inline screwdriver plays to its strengths: low force, low weight, short head. For everything else, reach for other tools. Sanding before polishing is a job for sanders, shaping film and lifting old stickers one for heat guns, and the tools category gives you the overview.

Besides matching bits and the plastic trim tool from further up, a magnetic tray helps make sure no screw goes missing during removal.

In the end, on plastic it's not the force a tool has that decides, but the force it holds back. A big drill driver can still strip a plastic boss even on its lowest setting; an inline screwdriver with seven settings up to 5 Nm works its way up to the joint in small steps. That's why the small screwdriver isn't a compromise in the interior, but the safeguard you build in before every detail.