UX Improvements

frontend/src/core/units/units.types.ts

@@ -6,7 +6,7 @@
 export type UnitSystem = 'imperial' | 'metric';
 export type DistanceUnit = 'miles' | 'km';
 export type VolumeUnit = 'gallons' | 'liters';
-export type FuelEfficiencyUnit = 'mpg' | 'l100km';
+export type FuelEfficiencyUnit = 'mpg' | 'kml';
 
 export interface UnitPreferences {
   system: UnitSystem;
@@ -21,4 +21,4 @@ export interface UserPreferences {
   unitSystem: UnitSystem;
   createdAt: string;
   updatedAt: string;
-}
+}

frontend/src/core/units/units.utils.ts

@@ -10,7 +10,9 @@ const MILES_TO_KM = 1.60934;
 const KM_TO_MILES = 0.621371;
 const GALLONS_TO_LITERS = 3.78541;
 const LITERS_TO_GALLONS = 0.264172;
-const MPG_TO_L100KM_FACTOR = 235.214;
+// For km/L conversion
+const MPG_TO_KML = 1.60934 / 3.78541; // ≈ 0.425144
+const KML_TO_MPG = 3.78541 / 1.60934; // ≈ 2.352145
 
 // Distance Conversions
 export function convertDistance(value: number, fromUnit: DistanceUnit, toUnit: DistanceUnit): number {
@@ -60,12 +62,12 @@ export function convertVolumeBySystem(gallons: number, toSystem: UnitSystem): nu
 export function convertFuelEfficiency(value: number, fromUnit: FuelEfficiencyUnit, toUnit: FuelEfficiencyUnit): number {
   if (fromUnit === toUnit) return value;
   
-  if (fromUnit === 'mpg' && toUnit === 'l100km') {
-    return value === 0 ? 0 : MPG_TO_L100KM_FACTOR / value;
+  if (fromUnit === 'mpg' && toUnit === 'kml') {
+    return value * MPG_TO_KML;
   }
-  
-  if (fromUnit === 'l100km' && toUnit === 'mpg') {
-    return value === 0 ? 0 : MPG_TO_L100KM_FACTOR / value;
+
+  if (fromUnit === 'kml' && toUnit === 'mpg') {
+    return value * KML_TO_MPG;
   }
   
   return value;
@@ -73,7 +75,7 @@ export function convertFuelEfficiency(value: number, fromUnit: FuelEfficiencyUni
 
 export function convertFuelEfficiencyBySystem(mpg: number, toSystem: UnitSystem): number {
   if (toSystem === 'metric') {
-    return convertFuelEfficiency(mpg, 'mpg', 'l100km');
+    return convertFuelEfficiency(mpg, 'mpg', 'kml');
   }
   return mpg;
 }
@@ -109,7 +111,7 @@ export function formatVolume(value: number, unit: VolumeUnit, precision = 2): st
 
 export function formatFuelEfficiency(value: number, unit: FuelEfficiencyUnit, precision = 1): string {
   if (typeof value !== 'number' || isNaN(value)) {
-    return unit === 'mpg' ? '0 MPG' : '0 L/100km';
+    return unit === 'mpg' ? '0 MPG' : '0 km/L';
   }
   
   const rounded = parseFloat(value.toFixed(precision));
@@ -117,7 +119,7 @@ export function formatFuelEfficiency(value: number, unit: FuelEfficiencyUnit, pr
   if (unit === 'mpg') {
     return `${rounded} MPG`;
   } else {
-    return `${rounded} L/100km`;
+    return `${rounded} km/L`;
   }
 }
 
@@ -166,8 +168,8 @@ export function formatVolumeBySystem(gallons: number, system: UnitSystem, precis
 
 export function formatFuelEfficiencyBySystem(mpg: number, system: UnitSystem, precision = 1): string {
   if (system === 'metric') {
-    const l100km = convertFuelEfficiencyBySystem(mpg, system);
-    return formatFuelEfficiency(l100km, 'l100km', precision);
+    const kml = convertFuelEfficiencyBySystem(mpg, system);
+    return formatFuelEfficiency(kml, 'kml', precision);
   }
   return formatFuelEfficiency(mpg, 'mpg', precision);
 }
@@ -190,5 +192,5 @@ export function getVolumeUnit(system: UnitSystem): VolumeUnit {
 }
 
 export function getFuelEfficiencyUnit(system: UnitSystem): FuelEfficiencyUnit {
-  return system === 'metric' ? 'l100km' : 'mpg';
-}
+  return system === 'metric' ? 'kml' : 'mpg';
+}