Personally would not bother as: -
1. many thermometers, even digital ones can be +-1c out, just compare several together.
2. depends where in the cabin / air vent you measure the temp ?
Do not forget the NTC means Negative, so the higher the temp the lower its resistance.
If the next value NTC gives a swing too high the other way, you could try adding a 1k trimmer pot in series with the NTC, which might allow you to balance it better, but seems a lot of messy work for such a small difference.