The resale value of these cars only increases or at least maintains as gas prices go up.
But 400k is not "high mileage", it's "astronomical mileage."
Just getting broken in.
Let's look at it another way. Mileage is actually a terrible way to rate a car's wear and tear. Like I said, I would rather have a 400k car that spent all of it's time at 2,000RPM @ 65MPH than a 200k car that saw stop and go with frequent climbs to 4500RPM+.
Anyway, according to my GPS my average moving speed has been 41MPH over the last 96,000 miles(since I got the GPS).
That means there is probably something like 3800 hours of moving time on my engine.
Since this car was used to travel back and forth between LA and the bay area, we can assume most of the miles are highway. If we assume that the car's average speed should therefor be considerably higher than mine, let's say 55MPH, the car's engine has 8,000 hours on it. If the car averaged 60MPH, that shaves a thousand hours off that figure. 3x as many miles as my car, only twice as many hours.
If my car's engine had logged 8,000 hours, the car would "only" have 328,000 miles on it. So that would be better, right? No. In the scenario I just painted, it wouldn't be. Shrug. I'm not worried at all.
If this were a Chrysler, then I would be worried. Honda got most everything right with this car as far as longevity is concerned. If the transmission goes out, the transmission goes out. That would be a worry with any used Insight though, and it can happen at any time. I won't feel very bad if I have to dump $1000 into a $2700 Insight. I would be pretty pissed if I bought a 5k specimen, and then had to turn around and replace the transmission though. Just trying to give perspective. At this price, there's a lot of room for broken stuff.