Why Top Gear got it ALL WRONG in 'Prius vs. BMW M3'

Top Gear TV Show Hosts photo

Top Gear: Prius vs. BMW M3

We're pretty certain that the Top Gear people know more about cars than we do, so they really have no excuse for this segment on the Prius vs. BMW M3. It almost seems like they try very hard to be misleading and avoid explaining why their "test" has pretty much zero real-world value. But lets start at the beginning... First watch the video below, then read on.

The Hybrid Car Battery Dilemma

The Top Gear segment starts with a mention that the battery used in the hybrid drivetrain of the Prius is made of materials that come from far away from the factory where the car is built. It's obvious when you watch it that what they're going for is an "Aha!" moment, and that they're trying to leave their viewers with the impression that hybrid cars are worse for the environment than regular cars.

Here's the reality-check:

Prius Battery: Green or Not?

Hybrid car battery packs indeed have an environmental impact, but so does everything used to make a car. Singling out the battery out of context doesn't paint the whole picture. To be honest, you would have to look at the whole cars; Where do materials to make the BMW M3 come from? Which car factory is greener and more efficient, Toyota's or BMW's? Once you've looked at all that, it might be that the Prius takes more energy to make than the BMW, but at least it would be a scientific comparison.

But making a car is just the start. Depending on which life cycle analysis you look at, the fuel makes up to 80%+ of the footprint of a motor vehicle. Even with just back of the enveloped math, it's not too hard to believe: If a car has a life of 15 years, is driven on average 15,000 miles per year and gets 21 mpg, that's almost 11,000 gallons of fuel (and many cars are on the road for more than 15 years, are driven more than 15k miles/year, and get less than 21 mpg....). At least a good portion of the car itself can be recycled (f.ex, find out what happens to a Tesla electric car battery at the end of its life). The fuel is lost forever.

So once you know this, the hybrid car battery starts to look like a good environmental deal. All parts of a car have an environmental impact, but few of them will actually save fuel like a hybrid battery.

Prius vs. BMW M3: The Test

Now the actual test: The Prius drove ten laps as fast as possible on a race-track, and the BMW trailed behind. It is so meaningless as to be funny. Much worse than Prius vs. Jeep Patriot Diesel.

Driving the Prius with the pedal to the metal (probably around 100 mph, a speed at which 99.99% of Priuses will never go - the exception is Al Gore Jr. who got caught doing over 100 mph) is taking away almost everything that makes the car fuel efficient. At that speed, electric motors don't help, regenerative braking doesn't help, and the stop-start anti-idling feature is useless. Only the low drag coefficient and low rolling-resistance tires are of use, but that is more than offset by the small 1.5 liter gasoline engine that has to hit RPMs way above its efficiency sweet spot.

On the BMW side, the M3 was designed to be driven fast on the German autobahns and its engine certainly wasn't breaking a sweat trying to keep up with the Prius.

So What Does 'Prius vs. BMW M3' Tell Us?
Well, if most of your driving is going to be done on a closed circuit racing track with the pedal to the metal, a Prius probably won't save you that much gas. If that's not the case, you can forget about this useless, misleading Top Gear segment. It would be good entertainment if they had explained why it's a flawed comparison, but they played it straight, so thumbs down.

Hybrid Cars
Toyota Prius vs Jeep Patriot Comparison is Deeply Flawed
Toyota Prius Hybrid: 1 Million Served
Green Basics: Hybrid-Electric Cars

Hypermiling and Saving Gas
Hypermiling Becoming More Popular as Gas Prices Rise
Honda Insight Hybrid Wins Hypermiling Competition with 124 Miles per Gallon
Nascar Driver Uses Hypermiling Tricks to Win Race
Hypermiling Couple Gets Two Entries in Guiness World Records Book

Related Content on Treehugger.com