I have a decent credit score (low to mid 700's) and I'm pretty sure I could get approved for a loan. I'll be taking a new job in a new state in a couple of weeks and I would like to get my wife a new(er) car as she will not be going with me initially. My new job pays nearly double my current salary, but I've been told that I won't get approval because I'm new to the job. Would it be better to go ahead and get the loan now or wait until my new effective pay rate takes effect?
If your current pay is sufficient to support the debt, it would be better to apply for the loan now, with more of a job history. Sufficient depends on the lender, but generally you need a debt-to-income ratio of 36% or less. Income means gross income (before taxes, 401(k), etc) and debt means all debt including the new car loan, mortgage, credit cards, student loans, etc.
If you need the new, higher income to meet the debt-to-income ratio, you'll have to wait and take your chances.