I just bought an 03 SLE and they offered a 4 year, 100,000, warranty that covered basically everything for $1800. I turned it down but they said I could go back and they can still do it. Is it worth it?

Hard to say definitively but in general, No.

This depends on the current condition of the car (how many miles on it now) and how handy you are with repairs that may come your way.
1800 seems steep but a lot can happen in 4 years.

Who'* the warranty company?
Did you read ALL the fine print?
Can you take the car to ANY shop, or just the dealer who sold it to you?
Do you have enough savings (or DIY-i-tude) to fix stuff off warranty?
Is this warranty transferrable should you sell the car?

It can be used anywhere - the dealer is a large dealership and would stand by it - I'm handy but not sure how much I want to work on a car anymore - The car has 55,000 miles on it - the drivers seat heat doesn't work - and I think it will need an intermediate shaft in the near future. I should have read this forum before I purchased!!! Mark

Those 2 problems are a real pita to work on.
Take it back and get those fixed asap, must have come with some waarenty as is?

If you read around here there are a few other gremlins that can nip you in the pocket book, the extended warrenty is up to you.