Sometimes, I feel bad about using an old diesel van. But then I look at the SUVs around me,...brand-new, oversized, and packed with horsepower and I wonder: Is my van really worse for the environment than these modern “efficient” cars?

My T4 can carry up to seven people, a bike, and whatever else I need. It has only 68 horsepower, and while it’s not the most aerodynamic, it runs on just 8 litres of diesel per 100 km. Meanwhile, new SUVs are heavier, faster, and have insane power, but we still call them “efficient” because of their consumption per km.

So I started asking myself, what if we’re measuring efficiency all wrong?

Efficiency is not about horsepower or acceleration

Today, we measure cars like they’re built for racing. 0–100 km/h times. Horsepower. Torque. Even fuel economy is framed as “better tech” rather than better design.

Manufacturers want us to believe that a Tesla Model Y (16 kWh/100 km) is more efficient than a Citroën 2CV (4.5L petrol/100 km). But what if that’s only half the story? So I thought about a formula that builds on efficiency from a sustainable point of view. 

Introducing the transportation efficiency index TEI 5.0 (it took some time to get the results straight)

A car’s true efficiency isn’t just how much fuel or electricity it burns—it’s how well it uses resources, space, and power.

This is how the Transportation Efficiency (TEI 5.0) Index works:

• Weight per passenger – More material = more environmental impact.

• Horsepower penalty – Excessive power is just wasteful engineering.

• Aerodynamic drag and tires – Oversized cars push a wall of air and burn more energy.

• Energy consumption per km – Both fuel and electric energy have costs.

• Battery & material impact – Mining lithium for a massive EV battery isn’t “green.”

The TEI 5.0 aplied to real cars

Results

The Citroën 2CV, designed in the 1940s, is more efficient than a Tesla Model Y.

The Tesla Model Y and Toyota RAV4 Hybrid score worse than old combustion cars.

The Dacia Spring Electric is the only modern car that actually makes sense.

Oversized modern cars like Suv's are the real efficiency problem

The industry masks inefficiency with technology. Instead of designing light, smart, efficient vehicles, we build 2.5-ton SUVs with 400 HP, then throw a giant battery in to make them “eco-friendly”. We’re designing cars for bullies. Big machines, big tires, aggressive acceleration. More power than anyone actually needs.

The Audi A2 (1999–2005) was an ultra-light (850 kg) aluminium car that consumed just 3L/100 km. 

It was a failure. Why? Because efficiency isn’t sexy (thats what marketings suggests).
Instead, we got SUVs that isolate drivers, encourage speeding, and make roads more dangerous.

A new vision for car efficiency

If we care about sustainability, we need to rethink what makes a car efficient.

• Forget 0–100 km/h acceleration - it’s useless in daily life.

• Stop worshipping horsepower - we don’t need 400 HP to get groceries.

• Design for lightweight, resource-conscious transport.

We need to stop comparing cars using outdated marketing metrics and start using real-world approaches like TEI 5.0. Because the future of transport isn’t about faster, bigger, or more powerful. It’s about doing more with less.