What type of oil are you running? Might not be the fuel so much as frozen oil not letting engine move as free as it would like. For that cold you need clean oil and cold rated oil. The synthetics are typically 0W-30 and sat they are good even colder then that rating allows. I've been getting down to zero here at night and with the synthetic/regular oil blend I run - a 5w-30 - I can feel the engine work to warm up.

This also goes for what is in tranny. Older dirty oil needs to be warmer before it lets things flow smoothly.

Check the fluid levels in both engine and tranny when warm and then when cold and see the difference! (Or if black/very dark change!)

This morning it was -15. I started up my car and began driving, I could not drive faster than 10 miles per hour, when I stepped on the gas, it was as if the flow of fuel did not increase. I suspect fuel lines or other hoses may be allowing moisture into the system. Also at this temperature if the car sits for 8 hours it not only has trouble coming up to speed, but also shifting...in warmer weather there are no issues. I had an issue with cold weather shifting in the past, but that was PNP switch related. I'm wondering if there is anything I can do to resolve this...after about 30-35 minutes the car seems to thaw out and drives normally. Any ideas?