80 MPH vs 70 MPH: Chevy Bolt Range Test Shows What Speed Really Costs You

Everyone knows driving slower saves range. What almost nobody knows is how much. Tom Moloughney of the State of Charge YouTube channel just put a number on it, running the 2027 Chevy Bolt through back-to-back highway range tests at 70 mph and 80 mph. The gap: 24 miles. That's not a rounding error — that's the difference between rolling into your driveway and hunting for a fast charger at 4% state of charge.

What the test showed

Moloughney drove a 2027 Chevy Bolt LT on a highway route averaging 70 mph and covered 243.1 miles. A team member then ran the same car, on the same route, on a different day, averaging 80 mph. Both runs took the battery from a 100% state of charge down to 1%, so this was a genuine apples-to-apples test that used the full usable capacity both times.

• 70 mph: 243.1 miles, 3.6 mi/kWh, 66.6 kWh used
• 80 mph: 219.3 miles, 3.2 mi/kWh, 66.3 kWh used
• EPA estimated range: 232 miles
• Net difference: about 24 miles, or roughly 10% of the car's total range

Notice that both runs consumed essentially identical energy — 66.6 kWh versus 66.3 kWh. The battery didn't change. What changed was how far that energy carried the car. At 70 mph the Bolt beat its EPA number by 11 miles. At 80 mph it fell 13 miles short of it.

0.4 mi/kWh sounds trivial. Over a 200-plus-mile run, it's 24 miles — often the difference between one charging stop and two. (Data: State of Charge, via InsideEVs)

Why EVs punish speed more than gas cars do

Gas cars are most efficient on the highway. EVs are the opposite — they're happiest in the city, where regenerative braking recovers energy and speeds stay low. Push an EV to highway speeds and aerodynamic drag climbs steeply, draining the pack faster with every mile per hour.

The idea isn't new. During the 1970s gas crisis, the U.S. government effectively dropped the national speed limit to 55 mph purely to conserve fuel. In the electric era, that same tactic works at least as well — arguably better, because the payoff isn't just money. In a combustion car, burning extra fuel to arrive sooner is usually worth it; gas stations are everywhere and a fill-up takes five minutes. In an EV, eking out extra range can be the difference between arriving and adding another 30-minute charging stop to your day.

The most interesting detail: the penalty shrinks as the battery drains

Here's the part that surprised us. The efficiency gap between the two speeds wasn't constant — it got smaller as the state of charge dropped.

• First 25% (100–75%): the 70 mph run went almost 11 miles farther
• 75–50%: the advantage narrowed to 6.9 miles
• Final 25% (25–1%): just 4.7 miles

In other words, the biggest cost of speeding happens at the top of the battery. That flips a common piece of road-trip advice on its head. If you're already low and you need to reach a charger, adding a bit of speed to get there sooner won't cost you nearly as much battery as you'd fear. Save your hypermiling discipline for the first half of the pack, when it actually pays.

Context: it depends heavily on the car's shape

The Bolt's 24-mile penalty is honestly modest, and that's a compliment to its small frontal area. Moloughney ran a similar comparison on the Escalade IQ at 60 mph versus 70 mph. At 60 mph, the big electric Cadillac managed a staggering 607 miles — a full 125 miles more than it achieved at the higher speed. A brick-shaped three-ton SUV pays a far steeper aerodynamic tax than a compact hatchback.

The lesson generalizes: the bigger and boxier your EV, the more your right foot matters. Cybertruck, Model X, and full-size electric truck owners will feel speed changes much more sharply than Model 3 drivers will.

What this means for EV owners

Range isn't only something you buy — it's something you manage. A few habits and a little gear recover a surprising share of what speed takes away:

• Set cruise 5–10 mph lower on long hauls. On a 250-mile leg, that's often one fewer stop. Do it early in the trip, when the efficiency payoff is largest.
• Keep tires at spec. Underinflated tires quietly bleed range on every single drive, and cold mornings drop pressure fast. A compact intelligent tire pump in the trunk takes 90 seconds to use and pays for itself in efficiency.
• Know your pressures in real time. A Bluetooth TPMS sensor set puts live per-wheel readings on your phone so a slow leak doesn't quietly cost you 15 miles of range.
• Consider aero wheel covers. Open-spoke wheels look great and cost efficiency. Aero disc wheel covers for Model Y and Model 3 Highland are the cheapest aerodynamic upgrade available to most Tesla owners.
• Carry the right adapter. Range only matters relative to charger availability. A NACS to CCS adapter opens up Tesla's Supercharger network to CCS cars like the Bolt, and our adapters collection covers the rest of the plug combinations.
• Charge full at home. Starting a trip at 100% from a proper Level 2 unit — browse our EV chargers — beats scrambling for a DC stop 40 miles in.

The bottom line

The 2027 Bolt turned in a genuinely strong result: 243 miles at 70 mph, comfortably past its 232-mile EPA estimate, from America's cheapest EV. Push to 80 mph and it drops to 219 miles. Both numbers are usable — but 24 miles is real money when you're watching the percentage fall and the next fast charger is 30 miles out. Slow down early in the trip, keep your tires right, and save the extra speed for the last quarter of the battery, where it costs the least.