That's a nice looking car you have there. You will likely be very happy with it. Mercedes diesels are very solid, smooth riding cars, and you'll soon be as obsessed with it as most of us are with ours.

I notice that your car was inspected - what did the inspection cover? Were the fluids and filters recently changed?
Have the brakes been inspected to determine whether there is enough lining on the pads? How about the brake fluid level
How about the drive belts? If there are any large cracks in them, or if the cloth backing is frayed or separated, these should be replaced before any long drive.
Do the radiator hoses leak?
Is the coolant level correct?
The flex disks (rubber discs on both ends of the driveshaft of the car) should be checked to ensure that they are still serviceable - if one of these fails you will be stranded - and it could possibly cause drivetrain damage.
Are the fuel lines leaking (including the small, cloth covered fuel return lines connecting the fuel injectors together)?

See www.dieselgiant.com for guidance on many of these items. Russell Parr offers a good overview of many of the common problems these vehicles have.

More things to check

- check the oil level - if the oil hasn't been changed recently - do this before the long drive (it takes 15W-40 oil) - a quick lube will NOT have the oil filter you need - you will need to go to a shop that specializes in foreign makes.
- check the air filter condition - if very dirty - replace it
- check the primary fuel filter (small, clear plastic device on inbound fuel line) if it looks black, or is chock full of particles, replace it.
- check tire pressure
- IF the tires are 10 yrs or more old REPLACE THEM - old tires can fail suddenly
Check the spare in the trunk for proper inflation

Find a mechanic in your area whom you trust and have him give the vehicle thorough inspection.

Your vehicle has 24 hour lifetime roadside thru Mercedes Benz. It's not free, but its there if you need it.