Formula 1 teams face having to split development programmes because rule tweaks, including those to help overtaking, for 2019 will have such a large impact on designs.
Following a lack of overtaking at the season-opening Australian Grand Prix, F1 chiefs and the FIA managed to push through a raft of changes aimed at helping cars follow each other closer next year.
The tweaks include new front and rear wing concepts, plus changes to the bargeboards and brake duct concepts.
Although the changes appear to be quite minor from the outside, teams have quickly come to realise that there will now be little scope for carry-over of parts from their 2018 designs to '19.
Renault technical director Nick Chester said: "It's made it quite a bit harder because, had we stayed with the same regs, you could have pretty much carried on developing your 2018 car and it would have been very similar to your '19 car. The split would have almost not been there.
"Now it's a really definite split. Any work you do on an '18 wing now you're not going to carry forward into '19.
"It's changed our philosophy of how we do our split."
As well as the aero changes causing a change of approach to wings, the increase in fuel allowance for next year will also force teams to build all-new chassis - something Force India was originally planning not to do.
Technical director Andy Green said: "For sure the changes were much bigger than we anticipated a month ago. We weren't even thinking about 2019 a month ago because it was going to be a continuation of current regulations.
"Then, all of a sudden, one or two of the teams decided that they wanted more fuel, an extra 5kg.
"That really scuppered next year's plans because that is a new chassis. We weren't planning to do a new chassis.