You need an impact wrench, don't get it confused with an impact driver.

Impact wrench

https://www.mitre10.co.nz/shop/makita-impact-wrench-18-volt/p/379465

Impact driver will do the trick for removal, for installation you'd ideally use a torque wrench with the correct settings. Alternately use the cars wrench to tighten as the length of it will only allow you to put so much torque into it.

I've heard too many stories of snapped (wheel) studs to use an impact to tighten anything on a car

Senecio:

You need an impact wrench, don't get it confused with an impact driver.

Impact wrench

https://www.mitre10.co.nz/shop/makita-impact-wrench-18-volt/p/379465

 

Whats wrong with a power bar and a torque wrench?

I would argue none for electrical. Especially if you don't know what you're doing. It's a good way to cross thread nuts/bolts or snap them.

For doing up nuts, use the bar that is with your car, that way you know you can take the wheel off to change it on the side of the road. Do them up tight obviously but not to the stage they are impossible to take off.

To take off nuts that someone has put on with a rattle gun without taking this into consideration - a breaker bar and the correct size socket.

https://www.repco.co.nz/en/tools-equipment/hand-tools/socket-accessories/mechpro-blue-breaker-bar-610mm-1-2in-dr-mpbsk103/p/A1295078?kwSearch=breaker%20bar

Annoys me no end when they use those rattle guns and over tighten the nuts - you pretty much cant humanly undo them unless you have the same appliance, or a very long handled wrench.

I remember a few years ago there were some complaints (Fair Go I think) about them being so over tightened they sometimes snapped off the studs!

Ideal tool for removing, is a impact wrench, (likely a 1/2" one), with a matching (impact rated) socket. Pretty much every one of the common power tool brands will offer one of these. These are extremely powerful, so great for getting stuff off, but very hard to monitor how much torque is being applied, so risk damage from over torque if used on the install. Something with a cira 300Nm breakaway torque should be plenty.

For tighting, you want something to use as a nut runner, and then manually do the final torque with a torque wrench

I imagine some torque wrenches have a nut running function (where they cut out almost immediately when met with resistance - My dewalt impact driver does this on setting 1).

But this (not available in NZ), with an adapter to suit a socket would be an ideal nut runner. Basically a compact drill with a clutch and, with a hex head, rather than a chuck.

https://www.amazon.com/DEWALT-DCF601F2-Brushless-Cordless-Screwdriver/dp/B07TXN17NS

In terms of the sorts of toruqe needed, most cars it comes in at 135Nm or less (135Nm for a landcruiser 100 series), but for a teala model S, 175Nm is specified.

A torque wrench is all well and good if you have a decent one and you keep it calibrated.

If you really want to use a power tool, these work:

https://www.bunnings.co.nz/ozito-pxc-18v-brushless-impact-wrench-skin-only_p6290566

I use one for 4WD trips.

When I bought mine from Bunnings it came in a kit with battery, charger and impact bits.  I can't find the kit on their site now.

edit: found it:

https://www.bunnings.com.au/ozito-pxc-18v-brushless-impact-wrench-kit_p0299325

another edit!  sorry that's AU Bunnings - maybe NZ don't stock the kits anymore.

I have an electric impact wrench in my Pajero.  I have a set off off-road wheels for for beach launching the boat and having an impact wrench makes it a quick and painless job.

Mine is a Makita unit that will do about 300 Nm. I chose it because I have a car charger for that system and because it was variable speed.

The wheel nuts need 115 Nm (according to manual).  When I'm refitting the road wheels, I tighten most of the way with the impact wrench and then go round and finish them with a manual torque wrench.  I'm getting quite accurate now with the impact wrench.  I'm less fussy with the off-road wheel as I'm travelling at max of 30kmh and short distances.

i'm not liking the idea of turning the nuts hundreds of times but i take the point about the start and the end

i will mount the nuts with my hands - my skinny hands are never strong enough to cross thread anything

and the last few turns also by hand

i just stand on the end of the 1+ foot tool that comes with most cars. i'm about 70kg. how many Nm torque is that?

PS so the shops that use airguns are ok?

the last shop i went looked a bit dodgy and they were using electric hand tool - probably an impact wrench as mentioned

Batman:i just stand on the end of the 1+ foot tool that comes with most cars. i'm about 70kg. how many Nm torque is that?

 

0.3m * 70kg * 9.8 (convert kg force to newton)  = 205 Nm