Toro Rosso technical director James Key admitted that knowing well in advance which power unit the team will be using in 2017 provides a huge convenience with regard to chassis design.
Last year, the junior bull outfit had its 2016 car pretty much completed when it was informed of a late switch from Renault to Ferrari power, a state of affairs which forced the Faenza squad to make design changes to its STR11 to accommodate the different engine.
Key underlined the luxury and huge advantage of designing its 2017 challenger with its engine partner as a known quantity.
"Massive. It's very difficult to describe how big it is," Key explained to Motorsport.com.
"We are really happy to know which engine we'll be using now. That was a very tough situation with this car.
"We were very late with the Ferrari engine. We didn't really have any information about the Ferrari engine, so we sat down with them in December and discussed things, so it was extremely late.
"The fact is you build the architecture of your car around the power unit installation, and it's so complicated now. It's so much trouble. An optimum car is based around the integration of the power unit."
While Key insisted his design team had done its best to adapt the Toro Rosso STR11 to the engine of its Ferrari partner, the months preceding the 2016 season involved a fair amount of guess work and compromise.
"We tried to minimise the impact of that, but inevitably there are knock-on effects. The car was a bit too heavy at the start of the year. We had some issues with some of the cooling parameters.
"Many other things weren't optimum, we had to make some guesses in some places. And it costs you a lot of money as well. To do that in such a short space of time costs you a lot of money.
"There are many, many things which even if it's difficult to tell when you see the car on the track, actually you know what's wrong with that car because you've had some compromises."
The team's 2017 car is now well underway, although Key remains somewhat cautious about its progress given next season's regulation changes.
"I think it's okay, we are sort of on schedule at the moment, although the schedules move depending on what you find.
"I know most people are pretty hectic now with their 2017 cars. It's very difficult to tell how you are doing because you don't know what other people are doing with the regulations.
"One of the hardest bits is knowing what makes a car with such massive regulations change tick. It's so difficult to tell at this stage.
"We are going down a route of really trying to understand what makes a good 2017 car and see if we can achieve it."
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