Engine names: what do they mean?

Tristan Young

19 Nov 2021

From TDI to E-Tech, car manufacturers have always loved to give their engines names, not only to offer a label so everyone know what’s under the bonnet, but also to convey a sense of ‘mine’s better than yours’ and hopefully woo more buyers. But what do they all mean?

For decades car makers have included an engine designation in the title of their cars in part to inform but also to promote.

These engine tags have been around so long that these days we take them for granted and worry little about what they actually mean or stand for.

So to rectify that situation, YesAuto has picked some of the newest, best-selling and longest standing engine names and found out what each stands for.

Before we get started, there are few basics that tend to apply across the board. For instance, in engine naming terms the letter ‘i’, upper or lower case, almost always stands for ‘injection’. Historically, ‘i’ signified electronic fuel injection rather than the use of a mechanical carburettor. However, now every modern car with a combustion engine uses fuel injection rather than a carburettor, which may make it seem like the ‘i' is a little superfluous to requirements.

And ‘D’ usually, but not always, stands for diesel. However, it’s designations such as this where confusion can begin to build; that’s because ‘D’ can also stand for ‘direct’.


Possibly one of the most well-known engine names is TDI, first used by VW Group. And while all TDI engines are diesels, the ‘D’ in TDI actually refers to direct, as in direct injection. The ‘T’ in this case – and almost all other automotive engine uses – stand for turbocharged.

Interestingly, Volkswagen’s own website doesn’t actually call TDI an acronym and give each letter a word, instead pointing out that it means “advanced diesel engines using direct fuel injection and a turbocharger”.

While we’re in Volkswagen Group territory, the manufacturer also uses a collection of related badges for its petrol engines including TSI, FSI, TFSI and eTFSI.

The ‘SI’ in all cases means ‘stratified injection’ which is VW’s term for running a higher compression ratio without engine knock, in reality this means a more efficient engine.

The addition of ‘T’ indicates the engine’s turbocharged and the ‘F’ stands for fuel. Simple enough, but that doesn’t really make it easy to differentiate between TSI and TFSI – because they both use fuel and they’re both turbo. In reality this is where the line blurs between a true engine descriptor and a marketing name as both use the same sort of technology.

And the ‘e’? Well that simply stands for electric or electrified and indicates the car’s a plug-in hybrid.

Keeping it simple

Some brands make it much simpler. Ford uses just two main engine descriptors; TDCi and EcoBoost.

In the first case it stands for turbocharged diesel common rail injection. Common rail describes the way the fuel is supplied to the cylinders.

Rather than using an acronym for its petrol engines, Ford is one of many brands that uses names to describe some of its engines and its current line up are called EcoBoost to signify their efficiency and the fact they’re turbocharged (boosted).

Names not letters

Ford isn’t alone in using a name for one of its engine families.

MultiAir is Fiat and Alfa Romeo’s term for a variable valve timing and lift and similar in idea to Honda’s VTEC (variable valve timing and lift electronic control).

PureTech is used on a family of three-cylinder engines from Peugeot-Citroen and rather than hinting at a specific technology it conveys a small yet powerful and efficient engine.

Possibly the best engine name, in this author’s judgement, is BoosterJet – especially if it’s read in a movie blockbuster voiceover style. BoosterJet [coming to a cinema near you] is Suzuki’s direct injection technology where fuel is pushed directly into the cylinder, rather than being mixed with air and then being injected. The technology improves combustion while keep emissions low.

Mix and match

A few manufacturers combine names and letters. Possibly just to keep things interesting, but more likely as a marketing tool to show buyers that what’s under the bonnet is the latest and most efficient technology.

Stellantis, which owns brands such as Peugeot and Citroen uses BlueHDI for some of its diesel engine where the HDI part stands for high-pressure direct injection and the ‘blue’ part really just refers to the fact these engines are more efficient than the original HDI units and often include stop and start tech.

In Renault’s latest E-Tech name is, again, more of a marketing badge denoting a hybrid or fully electric car, but for those hybrids E-Tech has two electric motors as well as a petrol engine.

No name

However, some brands just don’t include the names of their engines in the name of the car. It’s not exclusively the case, but the premium brands tend to stick to a simple power or engine size designation, possibly with a fuel type indicator. BMW, Mercedes and Lexus currently fall into this category and as does Jaguar Land Rover.

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Tristan Young

19 Nov 2021