The C indicates that our new long term Mondeo, a Zetec S hatchback, is powered by the excellent new common rail turbodiesel engine which means it has 130bhp on offer instead of the old di version's 115bhp.
But it is not just in terms of power that the TDCi is superior to the TDdi - the cars are about as similar as chalk and cheese.
It's true we clocked up over 10,000 miles in the old car at an average miles per gallon figure of 43.93 (not bad by any means), but we often complained that the TDdi was almost agricultural in terms of noise and refinement.
The TDCi engine takes Ford to the top of the upper-medium diesel table - comfortably able to compete with the previous sector leader, the Volkswagen Passat TDI PD 130.
With just 1,200 miles on the clock, our new model is proving a star. Several colleagues have commented on its good looks and the editor is already regretting that he handed over the keys to me last week in exchange for the Vauxhall Zafira - silly move, that, eh?
Part of the reason for the car's sleek exterior appearance is a set of snazzy alloy wheels and massively fat low profile tyres, together with metallic black paintwork. They've given the car a lower, leaner look than any diesel model deserves.
But fire up the powerplant and you'll find performance is most undiesel like too. After a rather rattly start at tick-over, the TDCi is whisper quiet at motorway speeds. 0-60mph comes at 9.9 seconds and maximum speed is a respectable 124mph. Trouble is the car is so smooth that it's easy to exceed the speed limit without realising.
On a trip along the M40 the other day, I found myself constantly having to ease off on the throttle as my speed crept up into plod-attracting territory.
Meanwhile inside, the front seats are a dream. There is plenty of lumbar and side support and a 300-mile trip to Oxfordshire came and went with never a back twinge. The interior trim gets my vote for styling. The dash is a classic wedge shape but the addition of lots of silver metal inserts among the black gives the whole car a sporting appearance.
Being a hatchback, there is plenty of room for luggage in the rear, which will be a boon as I am planning to move house soon.
I only have a few complaints. The first is that the clutch is so sharp that I have stalled the car on several occasions, once last week in front of 15 other journalists. My street cred among Britain's motoring press is now hovering somewhere below Old Kent Road.
Also, the car's enormous C-pillar and high back make reversing into parking spaces awkward.
The only way to do it safely is to hang out of the driver's door like a gorilla in a tree and look behind you.
Also, I'd like the side mirrors to be bigger. Where did Ford get them from - a dentistry supplier?
Those moans apart, I intend to hang on to the Mondeo's keys as long as possible. Uh-oh - the editor is already casting a beady eye in my direction!