Has anyone traded in there is250 for is350 if so was it difficult? How much did you pay? etc... Wanting to do it but my credit is ******. Thanks for any info.

 

There's just too many factors in such a deal to answer your question. Factors such as model year, miles on your car, condition of your car, the terms of your contract, what you may owe, if you've done mods, and more. And then there are the terms of the new car, such as year, options, purchase price, incentives, credit, financing, etc.
If you analyze each and all of those areas, you might get a better idea. Or simply go down to a dealer and see what he/she says. Just always do some homework on what your car is worth and what a new one should be purchased for (under invoice). Edmunds.com can help.
Good luck!