Odometer at pick-up (TDI): 4,072 km
Odometer final (TDI): 6,181 km (2,104 km by Autos.ca)
Observed Fuel Consumption TDI:  6.8 L/100 km
Fuel costs (TDI): $151.66
Fuel costs (Total): $396.64

To diesel, or not to diesel, that is the question. For years, now, the popular refrain has always been that we would take our compact wagon or hatchback in torquey diesel form, but these days, the answer is not so simple anymore. Diesel engines still deliver a significant fuel economy and torque advantage over gasoline counterparts of similar size and design, but the differences are shrinking, and the roller coaster fuel prices make estimating costs a moving target on a slippery slope, and I’m no good at horseshoes.

The TDI has come and gone, and we barely put a dent on its odometer, at least as far as our habits go, with a month of typical commuting and city driving, and unfortunately nothing to really stretch this efficient little diesel’s legs on a long highway cruise. Surprisingly, that is no longer the TDI’s big advantage. EPA estimates for the automatic-equipped Golfs have the combined mileage at 6.5 L/100 km for the TDI and 8.1 for the 1.8 TSI; highway consumption is a mere 1.0 L/100 km different, 5.5 to 6.5, but the city rating is 7.6 to 9.5, almost two whole L/100 km better.

Our results stayed pretty close the EPA figures, the 1.8T manual managing 8.1 L/100 km over 3,000 km, with at least 1,200 of those highway cruising, while the TDI was returned with over 2,000 km at a thrifty 6.8 L/100 km (thrifty for the very cold weather, snowy conditions and city driving it faced for much of its time with us).

In pure fuel costs, it was 8.0¢/km for the gasoline turbo, 7.2¢/km for the turbodiesel. Over 24,000 km per year, that would be $1,920 in fuel for the gas engine, $1,730 to fuel the TDI. And now to completely invalidate any conclusion you might draw from these calculations, these figures are based on shockingly low gasoline and diesel prices, gasoline at its lowest cost in years, dipping as low as 81.9¢/L in Brampton during its weeks with us, and diesel $1.059/L at its last fill-up. The EPA ballparks the difference between equivalent transmissions at about $50 (that using generally lower US fuel prices), while Transport Canada suggests that there might be over $300 difference in fueling costs. Throw in the occasional refilling of the AdBlue urea liquid, which can cost as little as that $50 difference. In other words, your mileage fuel costs may vary.

Of course, fuel is not the only cost of ownership, and Edmunds.com suggests that the cost of ownership will be several thousands higher for the gas model, factoring in depreciation, taxes, fuel, insurance and maintenance, most of the difference from insurance rates, so depending on insurance variable in your area, the difference may be negligible.

Overall, typical wear parts and maintenance costs will vary more by your service location than between gas and TDI models, which share many common parts outside the powertrain.

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