It seems to be intended that certain items are easy to steal (anything that doesn't lose functionality with wireless turned off), while other items are nearly impossible to steal (cyberdecks, commlinks). In the middle ground are items that don't work well or draw attention with wireless off (vehicles, medpacks, smartlinked weapons).
I would imagine that any large haul from a corporation will cause the items stolen to be placed on a high-priority list, with corporate deckers tracking down the corp-owned items the instant they appear on the Matrix. So, don't steal anything from a corp unless you plan to turn it into a throwback device, because the item will be way too hot to ever use in Wireless mode.
When you steal a car, take it to a contact with a shop, and assistants. A Teamwork Test between a mechanic and 6 assistants can make short work of a 24 threshold Hardware test. Figure maybe 12 dice for the head mechanic, each of the others adds 3 dice or so.. 30 dice for the first roll. Taking averages, it might be done in 2-3 hours. Charge your runners an appropriate fee for this service, say 20-30% of the vehicle's base cost?
I think you can't get more dice from Teamwork than the head mechanic's skill. So, if he's got a 6 Hardware, then he would get a maximum of +6 dice with the help of 2 or 3 assistants. That's still around 20 dice if the head mechanic is specialized for this sort of task, which would allow him to buy hits and finish in 6 hours, or roll and finish in an average of 4 hours.
By the rules, the easy solution is to get a Loyalty 6 contact to take the device off your hands at 30% of cost. That won't let you keep a really nice piece of gear (cyberdeck, drone, etc), but you don't have the network of people that most contacts have. Presumably, the contact has access to multiple people making Teamwork tests to get the necessary 24 successes, along with a decker ready to turn wireless off should a trace occur. They're probably working in an abandoned warehouse in the Barrens, and have a van inside the warehouse to evac quickly should a trace be successful. The contact should be able to sell restricted and forbidden items at a large profit (buy for 30%, sell for 100%). Even with the cost of multiple workers and a decker, that should be enough profit to make the operation viable.
I'm working on a character that has the skills to transfer ownership in Missions. With some advancements, he'll have a 10 Logic (Exceptional Attribute + Cerebral Booster 3) and a 5 Hardware. Buying hits, he can transfer ownership in 12 hours (9 hours if he takes Hardware to 6). He's also a decker, so he (or his Agent) can watch for an incoming trace and take the device offline at a moment's notice should the owner come looking. Fortunately, since this is done between adventures and you buy hits, there's no chance of discovery - you just take 1 day per item (7 items per Missions week).
EDIT: Transfer Ownership via buying hits (Chart)
Dice Hours Needed
34 3 hours (8+8+8)
27 4 hours (6+6+6+6)
23 5 hours (5+5+5+5+4)
20 6 hours (5+4+4+4+4+3)
18 7 hours (4+4+4+3+3+3+3)
17 8 hours (4+4+3+3+3+3+2+2)
16 9 hours (4+3+3+3+3+2+2+2+2)
15 12 hours (3+3+3+3+2+2+2+2+1+1+1+1)