You might be surprised to discover how few horsepower it takes to keep your car – or even a big SUV, for that matter – going.
Well, once it’s already going.
Last week, Dodge sent me a Durango SRT392 to test drive (the review of this beast is here). It has an interesting feature, a display that lets you know how many horsepower the engine is producing at any given moment – the number of them increasing or decreasing according to speed and load.
Once under way, as few as 40 or so horses out of the 475 that the Dodge’s 6.4 liter V8 is capable of producing are all that’s needed to keep the show on the road.
That’s about the same number of horses made by a classic VW Beetle’s much smaller four cylinder engine.
Of course, the difference is the Dodge can get to 60 about five times more quickly than an old Beetle – in four seconds or so vs. 20 or so seconds in the Beetle. And the Dodge can go much, much faster – in the vicinity of 150 MPH vs. around 80, if the wind is at your back, for the old Beetle.
The Dodge has a surplus of horsepower. The Beetle has just enough.
But when both are just cruising along at say 45 or so MPH on a flat, level surface – the same 40 or so hp is all it takes.
In part this has to do with gearing – leverage, really – the rest with inertia.