I'm going to put my KJ2 into storage for about 100 days.

The car will be in a dry and cool locked basement with no windows.

Other than disconnecting the battery, is there anything I should do?

Should I buy a cover for it, or is it ok without one?

Just leave the car as it is, make sure when you go to move the car there you give it a good run first up to full temp other than that I have stored cars for much longer and never had an issue

I had my car stored for 7 months, left the battery connected, started fine. I let it idle till running temp, then grandma drove for a day making sure everything was fine, then serviced it.

I always inflate the tyres to about 300 kpa when storing my car to avoid flatspotting them.

Only really need a cover if its gonna be out in the weather, if its locked up in 3 months time it'll just be slightly dusty, but other then that what madmagna said is sufficient

I left my car for 6 week once. It was out in the open. Started fine (battery died a year latter, was original as far as I could tell), only problem was the accelerator was stuck shut, but it freed itself up after a while.

Yeah I agree with what's been said - pump up the tyres super stiff to prevent flat spots. If you are anal and have a few jack stands you could even put it on the jack stands to eliminate any issues with the tyres. And as said, there's no need for a car cover if it's already in a basement.

Thanks guys,

So should I leave the battery connected or not?
Car has the factory alarm system, not sure how much power that drains?

On my cars I've always disconnected the battery when in storage. Just make sure you have the security code for the stereo (if needed).