Originally Posted by
chgoeditor
Congrats on planning in advance, bigvuth! However, keep in mind that there are countless factors which could cause major changes to your cost estimates four or five years down the road. Connected and automated vehicles have the potential to seriously disrupt the automotive industry, and it's tough to predict how that might impact the rental car sector. (Ditto if any of the major rental car companies go out of business, or if there is a new rental car company that adopts a "disruptive" business model -- one intended to shake up the rental car business, much as Uber and Lyft have changed the market for cabs -- that could also affect future prices.)
In 4-5 years, self-drive cars will not only be manufactured in commercially significant volume, regulatory and with insurance/legal issues resolved, but will be deployed such that rental car general practices and rates will be driven up in at unpredictable rate (e.g., more than average past increases and/or inflation)?? Not gonna happen.
The only somewhat likely event might be a rental car company going out of business, but we've seen that happen in the past - and there have been some recent mergers - without any significant impacts to major rental car policies and prices in most developed countries.
You could go crazy with "what-ifs"....there could also be nuclear war, the Second Coming of Christ, alien invasion, discovering we're in The Matrix, etc... but I'd say looking at current rental car prices and adding a bit of inflation factor - and monitoring as their travel time gets closer - is a pretty safe bet for the OP.
Aifrares - and award seat charts - are much more likely to be volatile than general rental car policies and prices...and in any case, would be a more significant chunk of OP's trip costs than the rental car.