will not running rc cars for months at a time ruin it?

i have 5 electric rc cars with lipo batteries and a nitro rc car that i havent messed with for months. will this ruin them if they are just sitting in my basement?

The batteries may have discharged and need to be recharged, and the Nitro car may have clogged lines, but other than that, they should be completely servicable (ie: cleanable and rechargable) that they work just as fine. Just remember, batteries do eventually die out on their own; where they won't hold a charge any longer (aka: the Memory Effect) which could mean that you may have to replace them.

Other than that, IF the batteries or the Nitro tank leaked, you may have some cosmetic or structural damage which may need to be repaired.

Hope that helps.

- Z