Here's the problem with SPF in foundation.  If you read the ingredients, other than mineral makeups, they don't contain UVA blockers.  You absolutely need both UVA and UVB protection every day, especially if you are in a car for your job.  Remember that UVA but not UVB goes through window glass!  

So please put your sunscreen on first (make sure it has a UVA blocker), then your makeup with SPF.  It's a win/win then.  

I love mineral makeups like the Jane Iredale or Bare Minerals because they protect against both UVA and UVB and look great on the skin.  They might be reasonable to use alone as long as you don't work outside or live in a sunny climate like LA , Florida, Arizona, etc.

I'll be back next week for more questions on my Q & A Blog.  Dr. I.