The transition from internal combustion to electric vehicles is not just a powertrain change — it is a complete redesign of the information architecture in the vehicle. An ICE instrument cluster displays speed, RPM, fuel, temperature, and gear. An EV instrument cluster replaces fuel with battery state-of-charge (SoC), RPM with power flow (kW discharge and recuperation), and gear with drive mode (eco/sport/regen level). New screens appear that have no ICE equivalent: charging session progress, range-to-charge-destination, energy recuperation efficiency, pre-conditioning status. EV HMI is not an ICE HMI with a few substituted labels — it is a substantially different information architecture that requires purpose-designed display software. This article covers the specific embedded GUI implications of the EV transition.
EV-Specific Display Content Requirements
Several display elements are unique to electric vehicles and require specific GUI design and data binding approaches:
- Battery State-of-Charge (SoC) gauge: The primary range indicator, replacing the fuel gauge. Unlike an ICE fuel gauge (monotonically decreasing), EV SoC can increase during regenerative braking — the gauge must correctly animate both charging (needle rising) and discharging (needle falling) transitions. SoC display accuracy is safety-relevant — incorrect SoC display could lead the driver to a stranded situation.
- Power flow display (kW): A live readout of instantaneous power draw (discharging) or recuperation (charging from regen). Many EVs use a bidirectional arc gauge — the needle swings right for discharge, left for recuperation. The data source updates at 10–100Hz from the BMS; the GUI must animate smoothly without aliasing or lag.
- Range display with dynamic recalculation: Estimated remaining range — derived from SoC × efficiency model. Updates continuously based on recent driving style and HVAC load. The range estimate changes significantly between motorway and urban driving. Display design must communicate the uncertainty of the estimate (not a precise value) to avoid driver anxiety from normal range fluctuations.
- Charging session UI: When plugged in, the cluster or infotainment transitions to a charging state — displaying SoC progress, estimated charge completion time, current charging power (kW), target SoC, and pre-conditioning status. This is a distinct screen mode with its own information hierarchy.
- Energy efficiency visualisation: “Eco scoring” displays — per-trip efficiency history, efficiency by driving factor (HVAC, speed, acceleration, braking) — are increasingly standard in EVs. These require small bar or strip charts updated on trip completion.
Display Consolidation: Fewer Instruments, More Software
The EV transition is accelerating a display consolidation trend: replacing physical instruments (analogue speedometer, physical climate controls, separate ADAS controls) with a smaller number of larger, software-driven displays. Tesla’s single centre screen approach is an extreme; the more common direction is a full-digital instrument cluster (replacing analogue gauges) plus a larger centre stack display (12–15 inch vs the traditional 7–8 inch).
For embedded GUI engineers, consolidation means: fewer separate ECUs driving separate displays, replaced by a cockpit domain controller (CDC) driving multiple displays from a single SoC (NXP i.MX 8, Renesas R-Car). All display content — cluster, infotainment, ADAS overlays — is rendered by a single domain controller with a capable GPU. The GUI software must manage multiple displays simultaneously from a single rendering pipeline.
OTA Updates Reshape the Development Lifecycle
Unlike ICE vehicles where instrument cluster firmware was effectively fixed after production, EV OTAs (over-the-air updates) regularly update display software post-sale. This changes the embedded GUI development model: GUI software must be structured for safe, incremental OTA updates (A/B partition, asset/firmware separation), and the product team must maintain UI consistency across the vehicle’s lifetime OTA update cycle.
For embedded GUI frameworks: OTA capability is now a first-class requirement in automotive GUI procurement. Frameworks that do not support OTA-friendly asset/firmware separation or that require full firmware reflash for UI changes are at a structural disadvantage in EV platform selection.
Electric Two-Wheelers: The Largest Volume EV Segment
In markets like India, China, and Southeast Asia, electric two-wheelers (e2Ws) vastly outnumber four-wheel EVs in unit volume. E2W instrument clusters are smaller (3.5–5 inch) and more cost-constrained than automotive clusters, but share the same EV-specific content requirements (SoC gauge, range display, charging status) at a lower BOM budget. This is a high-volume market with strong demand for cost-efficient embedded GUI solutions that support EV-specific display content.
For these compact and resource-constrained displays, Sparklet provides a lightweight embedded graphics foundation for implementing EV-specific interfaces such as SoC, range, power-flow, and charging visualisations. Its low memory footprint and hardware-accelerated rendering help deliver responsive, feature-rich HMIs while keeping system resources and implementation costs under control.
See EV charging station display, explore digital instrument cluster development, or view automotive HMI demos. Request the evaluation package to begin EV HMI development.