Last night my team was being chased by Lone Star and the TM in the group wished to hack the closest squad car and shut down the engine. What would you guys do in this case? Should it be possible if they're in signal range? Or should the car have to be outfitted with a control rig in order to be manipulated by a hacker?

If it's in range, you can hack it.

and if the car has a pilot rating (which by default it does) then the pilot can be made to shut down the engine (although given the temporary nature of that solution, i personally would have chosen to take it over and make it sideswipe another pursuing vehicle if possible).

given it's a security vehicle, i would assume the node has been upgraded to rating 4, if it was not already rating 4.

If it's a security vehicle it's not going to be easy. Any bored 12 year old can hack too....

And probably operates in 'hidden' mode and has some IC. Can be also watched by a security hacker.

Vehicle Nodes are usually encrypted - that will go double for Security Vehicles. Even if not using Strong Encryption, that probably means hacking it needs more time than available in combat.

That leaves Spoofing, which requires the Hacker to get the Access ID of a legitimate operator first, then issue the commad "stop engine". ("start engine" and "stop engine" should be legitimate remote commands to evade classic car bombs tied to those conditions.)

Hmm I wonder why wouldn't (security) vehicles, unless they're remote controlled, have their wireless disabled? You could still install a standalone communications node/commlink whatever. The movement systems need no wireless connection. But for game balance they probably would have.

You're missing facets of wireless technology that make it attractive to security companies (not the people driving these things, sure, but the companies that employ them). Without wireless connected to the vehicle itself you're looking at an increase in the costs of maintaining the vehicles - someone has to manually patch all of them and that someone has to get paid. You lose out on the oppurtunity to have them overseen remotely - leaving room to lose all data on part of the situation if a vehicle gets destroyed. Not to mention the ability to centralise your driving assets and actually leverage those Pilot programs.

Now, I can also give you reasons for the drivers to want wireless. First and foremost they would really like to have their vehicles move autonomously - nothing worse than having a ride a few blocks over that you can't get to because there's a street full of people who don't like you, or even having your ride damaged because you had to leave it standing unattended. Drivers don't have to position themselves in the front seat, and don't have to take any time plugging in or getting their hands into the controls with wireless - they can just bundle in and keep driving the vehicle.

People forget to switch their lights off when they leave their vehicle - why would manually switching wireless on entrance/exit be any difference?

additionally, having the vehicle wireless-enabled means that you can call in to HQ and request a full-blown rigger jump into the vehicle as backup; a regular officer probably has at least skill 2, probably 3, if they've taken the training program. reaction is probably also either 3 or 4. that's a dice pool of 7 + handling. not really any better than an upgraded pilot with an appropriate autosoft.

call in a rigger and you've got response 4, skill 3, specialisation 2 (this is a specialised rigger after all, not a generic officer), hot sim 2, and control rig 2. that's a dicepool of 13 + handling (11 + handling if you assume no specialisation), plus lowered thresholds on vehicle tests. and instead of having to train every single officer, you can just train a handful of them. they don't even have to be nearby; you could be a criminal in seattle and be chased by an officer in miami. and if we assume that they are above average (4 skill) and have the right nanites or are adepts, that could increase the dicepool by another 3. and did i mention that 4-5 IPs is easy to get in the matrix?

it isn't enough to beat a world-class rigger on average, but it's definitely better than the average go-ganger imo, and enough to give many riggers a challenge (or at the very least, more of a challenge than an officer with 2 IPs from jazz, regular skill and attributes, and no special equipment)

To do this the vehicle must have rigger adaptation which makes the vehicle more interesting for the enemy as well. Even if you want remote access for the rigger in HQ you could still slave the vehicle to a commlink or even the rigger's node. This makes the vehicle a lot more hacking proof.

It also helps vehicles interface with Gridlink and Gridguide - which can really help you get through traffic a lot faster. Also, pilot-only vehicles are hard to give new orders; you have to wait until they return to a specified access point. (And even that could be hacked, if ample time available.)

I'd set things up as follows:

1) Manual Override switch in the car, to be used if they think they're being hacked.
2) Pilot with ample autosofts and firewall - this is the default setting.
3) Rigger adaptation for extreme situations. A Rigger can be scrambled from HQ to drive the vehicle through extreme situations. Only heavily armored or special-purpose vehicles will have this, because riggers refuse to jump into things they can easily get injurious feedback from.
3a) If necessary, security hackers are also scrambled to deal with any attempts at hacking the vehicle.

Also, security firms might return the favor; hack the PCs' vehicle (those often have rigger adaptation, too...)