You can get a vehicle with armor higher than 6.
SR4A p86 quote:
All gear is subject to gamemaster approval—just because you can
purchase something doesn’t mean you should be allowed to get it at
the start of the game. Finally, no piece of gear purchased at
character creation can have a rating higher than 6 or an Availability
higher than 12 (for more information, see Availability & Buying Gear,
Now, let's take a look at page 69
Gear Ratings Some gear has ratings, beginning at 1 and increasing with
the capability and sophistication of the item. In addition to cost,
gear usually has an Availability, which determines how readily and
quickly the item can be obtained.
and 311, which treads on the same topic:
Device Rating: The Device rating determines the overall quality and
effectiveness of an item. When the item provides a bonus to certain
types of tests, apply the rating as a dice pool bonus to the test.
For example, a medkit with a Device rating of 3 would add three dice
to First Aid Tests, while a medkit with a rating of 5 adds ive dice.
In some cases, a Device rating may be used in place of a character’s
skill, such as a medkit that is hooked up to a patient and allowed to
work without a character’s supervision.
The gear rating limit of 6 can be interpreted in two ways:
- Device/gear rating limit of 6
- Limit of 6 on every of the gear's
attributes, which are accidentally called ratings as well (SR4A
In second case, I'd argue that availability is a rating, too, and one is therefore limited to availability 6 at chargen (and incidentally Restricted Gear is a useless quality). While SR4 have multiple cases of bad design, this would be a little over the top.
In first case, you're fine, since the vehicle doesn't have rating.