Leverage. The cross bars you usually find in the trunk don't work, even low torque impacts struggle, high torque impacts strip. A really nice two foot long breaker bar with a 1/2" socket end(and preferably the black impact grade sockets on it). I live in northern Canada where our lugs take a beating through all four seasons and we never lube them up. The breaker bar is your savior.
I used to get so frustrated using normal sized ratchets and wrenches and I always used a full can of WD-40 and still stripped or broke something. Leverage, leverage, leverage... even on rusty suspension! I have a compressor with an impact and I'll still use my breaker bar before I whip out the impact.
I learned a long time ago that the tire tools that the car comes with are useless. I keep a 1/2 inch, 25 inch long breaker bar and some 6 point deep well impact sockets in the van. I've had to stand on the breaker bar a couple of times, but I've never failed to get one off.