I do not know if my S40 is AWD or FWD , is there an easy way to tell which one it is?
AWD as VIDA read

 

Well the car should have badging that says AWD on the trunk lid, bottom right. Then there is the Haldex unit with driveshafts to the rear wheels.

 

Thank you, I look for those too. For now, it was easy to read vehicle specs by Vida All-in-one, it indicates AWD.
Now this car has 137000 miles,no service records. Is there a way to find if the timing belt that supposedly should be changed at 100000 miles, been changed or not?

 

the timing belt on your 2007 S40 is 10 years or 120K miles so it should have been done within the last year or so. Look under the hood for any stickers or markers that show when the timing belt was done. Some shops will use a permanent marker like a silver sharpee to write it on the top of the timing cover or use a sticker with the mileage. If not, have a shop pop off the cover to look - the idler and tensioner should have also been done so they and the belt should look new. Also to know more about your car, you can use a VIN decoder (plenty of online sites) which will say what your car's config is.

 

If there is any doubt, change it.