Index
A brief history: the evolution of petrol
Did you know that petrol has come a very long way since the 1920s? From the 63-octane fuels of that era to today's premium formulas, decades of research and development have produced increasingly efficient, environmentally responsible fuels.
In Spain, the use of lead in fuels was banned in 2001 due to its toxicity. While lead improved engine performance, it prevented the use of the catalytic converters needed to reduce harmful emissions. As a result, fuel companies began developing unleaded petrol formulas based on octane ratings — a far more responsible approach.
Over the years, petrol formulas have continued to advance in terms of both efficiency and composition, driven by the ongoing R&D efforts of major companies. The central ambition has always remained the same: to design fuels that maintain optimal engine performance while minimising environmental impact.
Types of petrol available on the market
Today, service stations typically offer two main options: Unleaded 95 and Unleaded 98, classified — as mentioned — by their octane rating. But what does this actually mean? The octane rating measures a fuel's ability to resist premature detonation when compressed inside the engine cylinder. As a general rule, the higher the octane rating, the better the performance — particularly in high-compression engines.
95 Petrol (Unleaded 95)
The most widely used option, 95 petrol suits the vast majority of cars and offers a solid balance between price and performance.
98 Petrol (Unleaded 98)
If your car has a high-performance or high-compression engine, 98 petrol — with its higher octane rating — may well be the better choice. You'll notice a sharper throttle response and, in some cases, even a slight reduction in fuel consumption.
Premium and additive-enhanced petrol
Within both the 95 and 98 ranges, premium versions exist that incorporate special additives for superior engine cleanliness, corrosion protection and improved performance. Premium petrol is, in general, a higher-quality fuel — specifically developed to get the very best out of modern petrol engines, while delivering enhanced engine protection and, as a result, meaningful savings in both fuel consumption and maintenance costs. Among other benefits, they offer:
- Extra protection against oxidation and corrosion.
- Prevention of emulsion formation if water enters the fuel system.
- Keeps injection systems and combustion chambers clean.
- Greater efficiency and better throttle response.
- A smoother, more enjoyable driving experience.
Types of petrol by price
Another way to categorise petrol is by price. In Spain, fuel distribution to service stations is managed by the Compañía Logística de Hidrocarburos (CLH), which ensures that the minimum quality standards set by law are met across the board. Building on this foundation, some companies develop their own proprietary blends to enhance the properties of standard fuels — which typically do no more than satisfy the minimum legal requirements.
- Low-cost petrol: Meets basic quality standards.
- Standard petrol: Contains specific additives that improve its properties.
- Premium petrol: A high-quality option with advanced technology, tailored for high-performance engines.
Things to consider when choosing your petrol
Beyond knowing the differences between diesel and petrol, it's important to understand which grade best suits your vehicle and your driving style.
Performance and engine type
The choice between 95 and 98 octane depends primarily on your engine's compression ratio. High-performance or sports engines typically require 98 petrol to run at their best and avoid engine knock. For most everyday cars, 95 petrol is more than adequate — and the grade your manufacturer will recommend.
Driving style: city vs. open road
If most of your driving is urban — short trips at low revs — 95 petrol will do the job perfectly well. If, on the other hand, you drive in a more spirited style or regularly push your engine on open roads, 98 petrol can deliver a sharper response and better protection for mechanical components.
Price and cost per kilometre
Although 98 petrol carries a higher price per litre, in high-compression engines it can improve efficiency and marginally reduce fuel consumption — which may offset the extra cost over time. That said, in an engine designed for 95, switching to 98 will bring no performance benefit whatsoever and will simply add to the cost at every fill-up.
Ultimately, the choice between 95 and 98 is not a question of "better" or "worse" — it's about finding the right fit. The key is to listen to both your engine and your budget: check your vehicle's handbook for the recommended octane grade and consider your driving habits. Just as octane rating is the decisive factor for petrol engines, the world of diesel brings its own set of considerations — cetane number, specific combustion additives and more. If you'd like to learn about diesel's particular characteristics and find the best option for diesel engines, don't miss our article on types of diesel.
