The 2007 on Mondeo 2.0TDCI is best in class: most reliable, nicest to drive, with sensibly priced servicing. But, like any diesel, you'll be up for a new timing belt at 60k miles, DPF and a new DMF and clutch at 80k - 120k. Another way would be to go for something with a long warranty, like a KIA cee'd. All 1.6s have timing chains, but the long warranty still won't cover things like DMFs and DPFs.