VTS (Vehicle Technical Specification)

The VTS (Vehicle Technical Specification) serves as the "paramount governing document" and top-level design blueprint throughout the entire automotive R&D lifecycle. Within the automotive engineering V-model development framework, the VTS bridges vehicle product definition, market positioning, and the Voice of the Customer (VOC), translating broad commercial and functional requirements into quantifiable, verifiable, and traceable engineering technical targets. It acts as the overarching design constraint across all vehicle domains (including powertrain, chassis, cabin, body, NVH, safety, and electrical systems). Downstream Subsystem Technical Specifications (SSTS) and Component Technical Specifications (CSTS) must strictly be cascaded, aligned, and channelled layer-by-layer from the VTS, ensuring no subsystem breaches the top-level red lines set by the VTS.

Core Technical Architecture and Documentation Scope

The VTS covers all dimensions of vehicle performance and physical constraints from the ground up, with its core framework typically structured around the following key macro dimensions:

Vehicle-Level Core Performance and Metric Definition (Vehicle-Level Core Performance and Metric Definition): 

Defines the overall physical dimensions and parameters of the vehicle (such as overall length, width, height, wheelbase, track width, laden ground clearance, kerb weight, and gross vehicle weight [GVW]), alongside core performance targets. This encompasses dynamic performance figures (e.g., 0–100 km/h acceleration time, top speed, maximum gradeability), efficiency and range metrics (such as WLTC combined fuel consumption, pure electric range, electricity consumption per 100 km), aerodynamic targets (vehicle drag coefficient $C_d$), and whole-vehicle thermal management operating thresholds.

Multi-Dimensional Regulations, Crash Safety, and Vehicle-Level Compliance Baselines (Multi-Dimensional Regulations, Crash Safety, and Vehicle-Level Compliance Baselines): 

Outlines mandatory national regulations across target markets, type-approval and certification standards, as well as stringent global crash safety benchmarks (such as frontal, side, and pole impact star ratings under C-NCAP, Euro NCAP, and IIHS). It also establishes overarching compliance frameworks for Functional Safety (ISO 26262), Safety of the Intended Functionality (SOTIF), Cybersecurity (ISO/SAE 21434), and Vehicle Electromagnetic Compatibility (EMC).

Safety Specifications and Engineering Constraints

Strict prohibition against prematurely freezing and cascading SSTS before core VTS safety metrics are validated (Prohibiting Freezing and Cascading SSTS Before VTS Core Safety Metrics Are Validated): 

The VTS serves as the "ultimate line of defence" ensuring the vehicle development programme avoids detours and disruptive directional missteps. Rushing development schedules by kicking off hard tooling while top-level VTS safety parameters remain ambiguous or misaligned is strictly forbidden. Any architectural design flaw at the top level will trigger extensive vehicle-level re-engineering down the line, resulting in astronomical financial losses and catastrophic project delays. 

Strict prohibition against omitting powertrain performance degradation boundaries and thermal coupling limits in the VTS (Prohibiting Omitting Powertrain Performance Degradation Boundaries and Thermal Coupling Limits in VTS): 

Vehicle performance baselines under extreme operating conditions—such as severe cold, intense heat, and high altitude—must be firmly locked during the VTS phase. Treating vehicle power derating or thermal runaway propagation limits (such as cabin evacuation time windows) ambiguously within the VTS is strictly prohibited. Any deficiency in top-level VTS constraints will leave downstream subsystem teams without clear design directives, inevitably translating into severe quality failures and critical safety hazards on the road.