resumeIn brief
On a short winter route, the engine spends most of its time outside its most efficient temperature regime.
Useful to know
The cold can increase friction in the engine and transmission and prolong the reach of an effective operating temperature. FuelEconomy.gov emphasizes that this particularly affects short trips. [1]
The difference is not just in mileage. Two routes of the same length may start at different temperature states and involve different energy users, for example, heating glass and fans. [1]
Practically, when comparing expense records, note whether the journey begins with a cold engine and what the weather is like. Do not explain each change by fuel quality or new failure without considering the mode.
We don't give a universal rate for every model. The data from specific tests have conditions, car types and temperatures. It also doesn't have to turn this principle into an arbitrary long warm-up in place; follow the directions for the real car.
Sources
For further detail and to check the information: