Car won't start on first really cold day.
 

Car: 2006 IS250 Temp went to single digits.

Well it started on the first time but it was running rough. The check engine light started flickering (not solid) so I shut it off. It hasn't stated since. The battery was bad (3.2v) so I replaced it and it and it still won't start. Sometimes it seems like it's about to start but it never does. Brake petal seems unusually firm too. Any ideas?

Running rough means you have an issue. You will need to get the fault codes for you to understand the fault codes. What kind of battery did you replace it with? How did your battery die? How old was the old battery? When did it last run?

I took it to the Toyota dealer. They claimed that my fuel was contaminated. I'm really confused by that because I had been driving on 2/3rds of a tank of that same gas. In any case it's been starting and running fine for the last week. I actually think I had the same issue as this thread. https://www.clublexus.com/forums/is-...-no-start.html I think the extreme cold did something.