"If I had to choose a thing that was likely to be the dominant factor for the season, I would choose neither the level of power nor the aerodynamic development," said Allison.
"I would say this year reliability is going to be absolutely fundamental."
As well as allowing teams to score consistently, a reliable car will also be crucial to providing a platform for development, particularly with only 12 days of pre-season testing available.
Ferrari launches its 2014 F1 car
Ferrari team principal Stefano Domenicali is confident that the team can improve its car during the season even though this has been a weakness in recent times.
"The season will be long, therefore it is important to start with a very reliable car at the beginning and keep having the development on the running side that was not there last year," said Domenicali.
"I am expecting the first days of testing to be very challenging for everyone.
"There are a lot of things to be tested, a lot of things to be checked."
Gallery: 2014 F1 cars
Domenicali added that the major rules change for 2014 offers Ferrari an opportunity to turn around its recent underachievement.
Ferrari last won the drivers' championship in 2007 and the constructors' championship a year later, but despite near misses for Fernando Alonso in 2010 and 2012 has not triumphed since.
"The technical challenge is, as far as I can remember, the biggest one that we have seen in the last decade of F1," said Domenciali.
"There is the opportunity to make sure that this challenge will be taken in the right way by our group of engineers.
"We have a totally new powertrain and a set of new regulations that are very interesting, but has to be really looked carefully at in depth to make sure that we take the opportunity to improve our level of performance."