Why do power and torque cause so much confusion?

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Real-world loads and hills reveal whether headline kW matches everyday use.

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If you’ve ever stood in a dealership parking lot wondering whether 110 kW is “enough,” you’re not alone. Most of us were taught to fixate on one big number: horsepower or kilowatts. The trouble is, that headline spec hides more than it reveals.

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Are you asking the wrong question about horsepower?

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Here’s the quick truth you can bank on: power (kW or hp) measures how fast the engine can do work, while torque (N·m) is the twisting force that gets you moving. Both matter. And the way they’re delivered across the rev range usually matters more than the peak.

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I’ve spent years helping buyers choose vehicles for city commutes, long SH1 hauls, Coromandel weekends, and towing through the Great Dividing Range. My favourite cautionary tale is Jess from Tauranga. She bought a tidy small SUV with a “healthy” 110 kW, then loaded it with the kids, dog, and a roof box. On the Kaimai Range, it felt flat and busy, constantly kicking down. Nothing wrong with the engine; the match was wrong.

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A surprising insight to hold onto: in simple terms, engine power equals torque times engine speed. That’s why a modest engine can feel punchy in town if it delivers torque down low, yet run out of breath at 100 km/h. And it’s why EVs feel so lively off the line.

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Usable power across the revs, not just the single top number.
Power-to-weight of the vehicle (and of the vehicle plus trailer if you tow).
Gearing, cooling, and ratings that turn engine output into safe, repeatable performance.

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Think of torque as a big lever and power as how quickly you can move that lever over time. A tall lever helps you budge a heavy object (towing, hills). Power determines how quickly you keep it moving as speed builds.

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What do the numbers mean once you’re on the road?

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Here’s the rational bit that connects the dots.

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- Power, torque and RPM are linked: P (kW) = torque (N·m) × RPM × 2π / 60 / 1000. Same story in imperial: hp = torque (lb·ft) × RPM / 5252. Fun fact: at 5,252 rpm, torque and horsepower values (in those units) are numerically equal.

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- Acceleration at speed depends strongly on power. Since power = force × speed, the available tractive force at a given speed is roughly P/v. That’s why high kW matters for overtaking at 100 km/h, while strong low‑rpm torque helps you roll away cleanly with a load.

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- Power-to-weight predicts feel. Two cars with 120 kW can perform very differently if one is 1,300 kg and the other 1,700 kg. Divide kW by tonnes for a quick reality check.

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- Towing is about the whole system. Torque helps at low speed, but legal and safe towing depends on braked vs unbraked limits, GVM (Gross Vehicle Mass), GCM (Gross Combination Mass), towbar rating, and towball mass (typically around 7-10% of trailer weight). In AU/NZ, unbraked trailers are commonly capped at 750 kg.

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- Drivetrain losses are real. Wheel power is often 10-20% lower than engine (crank) power in traditional ICE drivetrains. That’s why two cars with “the same” kW can feel different on the road.

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- EV twist: electric motors deliver near‑instant torque at zero rpm, making them feel quick off the line. But for long hill climbs or heavy towing, check continuous power and thermal limits, not just the eye‑catching peak number.

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A practical cost of getting this wrong: at 100 km/h, a car that takes two seconds longer to reach passing speed needs roughly another 55 metres of road. That’s the distance between “no worries” and “why is that truck getting closer?”

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How power and torque show up on the dash during a real passing manoeuvre.

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What happens if you get this wrong?

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Picture this. You’re on SH2 behind a caravan. The passing lane opens. You indicate, nail it, and… nothing much. The engine flares, the cabin fills with noise, and the gap you were banking on evaporates. You fall back in line, heart thumping, partner shooting you the look.

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Now the other version. Same road. You’ve chosen a car that makes a flat, useful band of torque from 1,800-4,500 rpm and has a comfortable 70-85 kW/tonne. You roll on, it gathers pace without protest, and you tuck back in with metres to spare. Your pulse stays where it should.

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Or Mark in Newcastle, who bought a torquey ute but overlooked towball mass and GCM. First long downhill with the camper, the rear squatted, the fronts got light, and the brakes faded. It wasn’t a torque problem; it was a match-up problem. The right choice is about confidence as much as numbers: being able to pack the kids, hitch the boat, and go without nagging doubt.

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So how should you decide?

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Use this simple PACE framework before you read another spec sheet.

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P People and payload: How many on board, how much gear, roof boxes or racks? Heavier loads push you toward broader torque and higher kW/tonne.
A Activities: City only, mixed, hills, or towing? Be honest. Occasional towing is different from hauling a caravan to Taupo every second weekend.
C Conditions: Terrain, heat, and headwinds matter. Hot summers and long climbs demand strong cooling and sustainable power, not just a big peak.
E Efficiency and ownership: Bigger engines cost more to buy and fuel; EVs are brilliant for city torque but check charging, range with loads, and continuous output for long tows.

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A quick buyer’s framework:

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Target power-to-weight (vehicle as driven): city 45-60 kW/t; mixed 60-80 kW/t; hilly/highway 75-100 kW/t; performance 120+ kW/t.
Towing: base your thinking on combined mass (vehicle + trailer) and ratings (GVM/GCM, braked capacity, towbar/TBM). Power helps; ratings rule.
Usable band: look for low‑rpm torque for urban and towing; strong midrange for highway passing; a wide “sweet spot” beats a peaky top end.

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What are the practical steps to choose the right power?

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Follow this process and you won’t second‑guess yourself later.

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\n Do two quick sums\n
- Convert if needed: 1 kW ≈ 1.341 hp; 1 hp ≈ 0.7457 kW. 1 lb·ft ≈ 1.356 N·m.
- Power-to-weight: kW ÷ vehicle mass (tonnes). Example: 120 kW and 1.5 t = 80 kW/t.
- Torque-to-revs sense check: P (kW) = torque (N·m) × RPM × 2π / 60 / 1000. Example: 320 N·m at 2,000 rpm ≈ 67 kW; at 4,000 rpm ≈ 134 kW.
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\n Match use case to ranges\n
- City commuter, light loads: 50-90 kW (≈ 67-120 hp) in a light car can be fine, especially with a responsive auto/CVT or an EV.
- Mixed driving (family hatch/small SUV): 90-150 kW (≈ 120-200 hp) gives comfortable passing and headroom with passengers.
- Regular highway, hills, or frequent passengers: 120-220 kW (≈ 160-300 hp), with a broad torque curve or well‑tuned turbo.
- Towing/hauling: focus on ratings first. For light boats/campers (up to roughly 1,500 kg braked), mid‑size SUVs/utes with 130-200 kW and strong low‑rpm torque are common. Heavy towing demands a properly rated ute or wagon, often diesel, with several hundred N·m and the right cooling, axle ratio, towbar and brake setup.
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\n Mind the measurement gotchas\n
- kW vs hp vs PS (metric horsepower) aren’t identical. Many brochures use PS; 150 kW ≈ 201 hp ≈ 204 PS.
- Engine (crank) figures are higher than wheel figures due to drivetrain losses.
- Peak numbers happen at specific RPMs. Look for the curve, not just the summit.
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\n If you’re considering an EV\n
- Celebrate the instant torque for city and mixed use.
- Check continuous power and thermal management for long climbs or towing.
- Expect range to drop with roof boxes, headwinds, and trailers; plan charging accordingly.
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\n Test like you’ll live\n
- Bring the people and gear. Drive a steep hill and a 100 km/h merge. Feel for midrange pull, not just off‑the‑line snap.
- If towing, confirm: braked capacity, GVM/GCM, towbar rating, and towball mass (often 7-10% of trailer weight). In AU/NZ, unbraked trailers typically top out at 750 kg. Ensure trailer brakes if you’re above that and comply with local rules.
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\n Common objections handled\n
- “More is always better.” More kW helps at speed, but oversizing can add cost, weight, and fuel use. Aim for the right kW/tonne and a broad torque band.
- “Turbos solve everything.” Turbos add midrange muscle, but cooling and ratings still govern towing. Don’t skip the factory towing package.
- “EVs can’t tow.” Many can tow well for moderate distances; the key is planning for range and confirming continuous output and cooling.
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Stop chasing the biggest peak number.

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Choose usable shove across the revs, matched to your mass, terrain, and tasks. Do the quick kW/tonne check, verify ratings if you tow, and test drive the way you actually drive. Get that right and the car won’t just “have enough power.” It’ll feel calm, capable, and yours.

How Much Engine Power Do You Need?