HELP & FAQFrequently Asked Questions
Everything you need to know about EV operational economics, formulas, and data privacy.
🇺🇸 How much does it cost to charge an electric car in the US compared to gas at $3.50/gal?
At the US national average electricity rate of $0.16 per kWh, driving an EV achieving 3.8 miles/kWh costs approximately 4.2 cents per mile ($0.042/mi). In contrast, an internal combustion car averaging 28 US MPG with gasoline at $3.50 per gallon costs 12.5 cents per mile ($0.125/mi). For an average American commuter driving 15,000 miles annually, charging an EV costs just $630/year versus $1,875/year in gas—saving over $1,245 every year in fuel alone.
🇺🇸 Can I claim the $7,500 Federal Clean Vehicle Tax Credit for an EV in the US?
Yes. Under Internal Revenue Code Section 30D (Inflation Reduction Act), qualifying new electric vehicles assembled in North America that meet critical mineral and battery component guidelines are eligible for up to a $7,500 federal tax credit. Eligible buyers can transfer the full credit to registered car dealers at point-of-sale for an immediate price discount. Pre-owned electric vehicles under $25,000 can receive up to $4,000 (30% of sale price) in federal tax credits.
🇺🇸 What is cheaper in the US: charging at home (Level 2) or Tesla Superchargers?
Home Level 2 (240V) charging is dramatically cheaper. Overnight residential electricity rates average $0.08 to $0.16 per kWh, meaning a full 60 kWh battery charge (providing ~240 miles) costs only $5 to $10. In contrast, commercial DC fast chargers and Tesla Superchargers cost $0.35 to $0.48+ per kWh ($21 to $29 per charge). For optimal economics, charge overnight at home for daily commuting and reserve Superchargers for long-distance highway road trips.
🇬🇧 How much does it cost per mile (p/mile) to drive an EV in the UK compared to petrol?
With UK petrol averaging £1.45 per litre (£6.59 per Imperial Gallon), an average 40 Imperial MPG petrol car costs 16.5p per mile. In contrast, an electric car achieving 3.8 miles/kWh charged at home on a smart EV tariff like Octopus Intelligent Go (7p/kWh) costs just 1.8p per mile—an 89% fuel cost saving. On the standard Ofgem energy price cap (24.5p/kWh), an EV costs 6.4p per mile, saving over 61% compared to petrol.
🇬🇧 What is the cheapest way to charge an electric vehicle in the UK?
The cheapest method is home charging on a dedicated time-of-use smart EV tariff, such as Octopus Intelligent Go (7p/kWh off-peak window from 11:30 PM to 5:30 AM) or British Gas EV tariff. Fully charging a 60 kWh battery on Octopus Go costs only £4.20 (~230 miles range). Under the Ofgem standard price cap (24.5p/kWh), the same charge costs £14.70, while motorway public rapid chargers (79p/kWh) cost approximately £47.
🇬🇧 What are the UK Company Car Benefit-in-Kind (BiK) tax rates for electric cars?
Pure zero-emission electric vehicles enjoy an ultra-favourable UK Benefit-in-Kind (BiK) tax rate of only 2% for 2024/2025, rising by 1% per tax year to 3% in 2025/2026, 4% in 2026/2027, and 5% in 2027/2028. Equivalent petrol and diesel company cars carry BiK tax rates of 25% to 37%, allowing UK drivers and businesses to save £2,500 to £6,000+ every year in personal income tax and National Insurance contributions.
What is VoltSavings and how does the calculator work?
VoltSavings is an independent, 100% free financial modeling tool that computes the operational cost difference between petrol/diesel combustion engines and electric vehicles. You input your daily commute, fuel price, electricity rate, and efficiencies. The engine computes cost-per-km, annual savings, 5-year compounding ROI, and tailpipe CO₂ emissions avoided. For the full mathematical formulas, see our Methodology Page.
What does EV Efficiency (km/kWh) mean?
In combustion engines, efficiency is measured in distance per unit of liquid fuel (km per liter or MPG). In electric vehicles, energy is measured in kilowatt-hours (kWh), equivalent to 1 unit of electricity on your domestic utility meter. A rating of 30 km/kWh means the vehicle travels 30 kilometers using 1 unit of electric energy.
What typical efficiency numbers should I enter?
Electric Bikes / Scooters: 25 to 45 km per kWh (or 15 to 28 mi/kWh).
Electric Compact Cars / Sedans: 5.5 to 7.5 km per kWh (or 3.4 to 4.6 mi/kWh).
Electric Crossovers / SUVs: 4.0 to 5.5 km per kWh (or 2.5 to 3.4 mi/kWh).
Petrol 70cc-125cc Bikes: 40 to 55 km/L.
Petrol 1000cc-1800cc Cars: 11 to 16 km/L.
Does this calculator account for maintenance & engine oil?
Yes. VoltSavings provides inputs for routine monthly maintenance for both vehicles. In real life, internal combustion engines require frequent motor oil changes, spark plugs, timing belts, and transmission fluid. Electric vehicles have single-speed reduction gearboxes and regenerative braking, reducing mechanical maintenance by 60% or more.
How does home charging cost compare with public DC fast chargers?
Overnight home Level 2 charging on residential off-peak tariffs is where 85% of your savings are created. Public DC fast chargers carry infrastructure surcharges, costing 2x to 3x more per kWh than home electricity. For optimal economics, charge overnight at home and reserve DC fast chargers for long-distance highway travel.
How long do EV batteries last before requiring replacement?
Modern Lithium Iron Phosphate (LFP) battery packs are engineered for 2,000 to 3,000 full charge cycles, which typically equates to 250,000 to 400,000 kilometers (10 to 15 years of daily commuting). Read our detailed EV Battery Lifespan & Degradation Guide for practical charging tips.
Is my personal driving history logged or tracked?
No. VoltSavings operates 100% client-side in your web browser. We do not track your location, require an account, or send your inputs to a remote database. Learn more in our Privacy Policy.
Can I export or print an executive PDF report?
Yes. Click the 'Download PDF Report' button in the calculator results area. A dedicated print stylesheet will format your exact inputs, monthly cost delta, 5-year projection, and CO₂ savings into an executive one-page document.
