Which Audi Q8 is better: petrol or diesel?
Available in South Africa since 2019, Audi’s Q8 currently caps off their local flagship passenger car range. And, while there are more engine options available in overseas markets, we only have a choice of two 3.0-litre V6 powerplants – one running on petrol, and the other on diesel. Which one suits this large SUV best?
Which 3-litre is better?
First launched in turbopetrol form only, the turbodiesel joined the range a few months later. The newer addition has less power than the petrol variant, but a useful helping of extra torque in compensation. However, in spite of the diesel’s lower power output, the Q8 45TDI quattro is significantly more expensive than the more-potent (but otherwise identically-specced) Q8 55TFSI quattro – to the tune of a R 51 500 difference. Can the diesel really justify its price premium?
It should be noted that both of these cars are very expensive, with the 55TFSI opening the range at R 1 397 500, and the 45TDI clocking in at R 1 449 000 – before adding any options. Delving into the options list will easily add an additional R200 000 to their list prices, although even the base trim Q8 is very well-equipped.
Related: Find out more about the Q8’s standard equipment in our launch report.
Let’s take a look at the two options, before discussing which one would be the better buy.
|
|
Audi Q8 45TDI quattro |
Audi Q8 55TFSI quattro |
|
Engine Type |
3.0-litre, V6, single turbo diesel |
3.0-litre, V6-, single turbo petrol |
|
Power/Torque |
183 kW/600 Nm |
250 kW/500 Nm |
|
Performance Data * |
0-100 km/h in 7.0s, 220 km/h |
0-100 km/h in 5.9s, 250 km/h |
|
Fuel Consumption * |
7.8 ℓ/100 km |
9.1 ℓ/100 km |
|
Base Price |
R 1 449 000 |
R 1 397 500 |
* Manufacturer’s claimed figures for performance and average fuel consumption.
Which engine is right for you?
Both engines are mated to the same 8-speed torque converter automatic gearbox and Audi’s quattro all-wheel drive system. All these things are heavy, and, combined with the Q8’s considerable size and feature-heavy specification sheet, result in kerb weights of 2 145 kg for the 45TDI and 2 095 kg for the 55TFSI. Consequently, it needs quite a lot of power to move around – hence the torquey engines on offer. (Depending on local market demand, we might see sportier derivatives soon, with up to a 441 kW/800 Nm twin-turbo petrol V8 on the potential menu.)
For the range as it currently stands, the 55TFSI starts off with an immediate performance advantage, thanks to both its 50 kg weight advantage and that 67 kW of extra power. Compared to the 45TDI’s claimed 0 – 100 km/h sprint time of 7.0 seconds and top speed of 220 km/h, the 55TFSI is a lot more fleet of foot, with the same metrics improving to 5.9 seconds and 250 km/h, respectively.
Unfortunately, with the emhanced performance comes quite a serious fuel consumption penalty. According to Audi’s claims, the Q8 55TFSI has an average fuel consumption of 9.1 ℓ/100 km, but in the real world, even conservative drivers will more likely return mid-to-high 10 ℓ/100 km figures in mixed-cycle driving. By contrast, the 45TDI has an official average figure of 7.8 ℓ/100 km, and previous experience with other VW Group products using this engine has shown that sub-9 ℓ/100 km average figures are possible. Both cars will be a lot more frugal in steady-speed cruising, however, and the 45TDI should be able to better 7.0 ℓ/100 km on a long trip. (The 55TFSI will struggle to dip below 9 ℓ/100 km, unless the cruising speed is kept comfortably low).
Fuel efficiency is only part of the equation, though. Of greater significance is the nature of the power delivery, and that’s where the two Q8 derivatives are very different. While the TDI has more torque at its disposal, it’s only available over a very narrow rev band. The automatic gearbox keeps it operating in this most-optimal range, but the diesel simply doesn’t have the similarly-sized petrol engine’s top-end stamina and wide torque spread.
As a result, the TDI is more useful for towing or carrying heavy loads, ideally over long distances, while the TFSI is more athletic, with a more-linear power delivery and a free-revving nature. On road, the 45TDI also feels less frenetic in normal driving, with its abundance of low-rev torque giving it a gentlemanly character, unlike the 55TFSI’s more high-strung personality.
Related: The Audi Q8 put up a strong showing when compared to two of its main rivals.
The Verdict
The Q8 45TDI will be just the ticket for buyers who frequently travel long distances, or those for whom towing power is a priority. Both Q8 derivatives have a braked tow rating of 3 500 kg, but the TDI’s extra torque will make uphills and heavy loads that bit easier to handle. It’s also considerably more frugal, so buyers who dislike service stations will also prefer the 45TDI.
But, considering its much lower list price and superior performance, the Q8 55TFSI makes more sense. Its lower kerb weight (thanks to the lighter engine) means that its handling is a bit more agile, and the engine is fairly charismatic when it’s wound out to its 6 400 r/min redline. Even if the 55TFSI is not the fuel-saver’s first choice, it’s definitely the nicer one to drive, and that initial saving of R 51 500 can buy a lot of extra petrol to offset its higher thirst.