What does 45tfsi mean at the back of an Audi?
4 Answers
Audi's 45tfsi at the back is used to distinguish the power and acceleration of the car's engine. The number 45 represents a quantitative value of the car's acceleration, while tfsi refers to the engine's fuel stratified injection technology. Essentially, tfsi is an FSI engine equipped with a turbocharger. Taking the Audi S4 as an example: it is a mid-sized car under the Audi brand, with dimensions of 4770mm in length, 1847mm in width, and 1404mm in height, and a wheelbase of 2825mm. It features a front-engine, four-wheel-drive layout, with both front and rear suspensions being five-link independent suspensions. It is paired with an 8-speed automatic transmission and is a four-door, five-seater sedan.
After driving for so many years, I'm quite familiar with Audi's badge system. That 45TFSI at the back isn't simple—the number represents the engine's power level. A number like 45 roughly equates to around 245 horsepower, calculated using an official formula that converts torque acceleration. TFSI is the real technical core, combining turbocharging with stratified fuel injection technology, making it more fuel-efficient and powerful than regular turbo engines. Essentially, this label differentiates between various power levels, which is much smarter than directly displaying displacement. When you see 20TFSI, you know it's the entry-level, 55TFSI is the top configuration, and the 40s are the mid-range performers. In my opinion, Audi's labeling system is the most intuitive among the German Big Three (BBA), and focusing on this number when choosing a car is always a safe bet.
Last time I accompanied a friend to choose a car, I pondered this question. The 45TFSI number sounds impressive, but it's actually a power level code, not the displacement at all. Audi has devised a complex calculation formula that integrates horsepower and torque into this number, with 45 roughly corresponding to the high-power version of the 2.0T. The key lies in the abbreviation TFSI, which stands for turbocharging plus stratified combustion technology, offering about 15% higher combustion efficiency than regular cars. Interestingly, the same engine can have different numbers in different models. For example, both the A4 and Q5 use a 2.0T, but the tuning varies, resulting in different tail badge numbers. When comparing cars, it's advisable to directly compare the numbers. A 45 is considered ample in sedans but barely sufficient in SUVs.
My neighbor Old Wang just got an A6 with the 45TFSI badge. I've studied this labeling system - the number indicates the power tier, not the actual displacement. The 45 roughly equates to the performance of a high-power 2.0T version. The key lies in the TFSI technology, which combines turbocharging with direct fuel injection, delivering exceptionally smooth acceleration push. Interestingly, Audi adopted this system to replace the old 1.8T/2.0T labels, avoiding labeling awkwardness caused by emission regulations. A higher number doesn't necessarily mean larger displacement, but the driving experience is definitely more aggressive. I remember comparing the 40 and 45 versions during test drives - when overtaking in the same road conditions, the 45 felt much more effortless.
