MPG Calculator Logo
  • Vehicle MPG Checker
  • Compare Vehicle MPG
  • Fuel Savings Calculator
  • Road Trip Cost Calculator
  • Send Feedback

Fine Print

  • Terms of Use
  • Privacy Policy
  • Disclaimer
  • Contact Us

Useful Tools

  • Road Trip Cost Calculator
  • Fuel Savings Calculator
  • Vehicle MPG Checker
  • Compare Fuel Economy

About

MPGCalculator.net provides useful fuel efficiency tools and content to help you make informed decisions about vehicles.

Last Updated: 6/8/2025

© 2025 MPGCalculator.net. All rights reserved.

2004 BMW 645ci Convertible

MPG & Fuel Economy Data

Quick Summary

The 2004 BMW 645ci Convertible has an estimated 16.0 MPG combined. This premium gasoline-powered vehicle offers 13.0 MPG in the city and 21.0 MPG on the highway.  Check out its full EPA-estimated fuel economy data below.

Premium Gasoline Fuel Economy

Combined16.0 MPG

City13.0 MPG

Highway21.0 MPG

Recommended*

EVIQO Level 2 EV Charger - 48 Amp EV Charger Level 2-240V Electric Vehicle Charging Stations - Smart Wall EV Chargers for Home Level 2 - NEMA 14-50/Hardwired - 11.5kW EVSE J1772, Energy Star/UL

EVIQO Level 2 EV Charger - 48 Amp EV Charger Level 2-240V Electric Vehicle Charging Stations - Smart Wall EV Chargers for Home Level 2 - NEMA 14-50/Hardwired - 11.5kW EVSE J1772, Energy Star/UL

View on Amazon
Autel Home Smart Electric Vehicle (EV) Charger up to 50Amp, 240V, Indoor/Outdoor Car Charging Station with Level 2, Wi-Fi and Bluetooth Enabled EVSE, 25-Foot Cable(Dark Gray)

Autel Home Smart Electric Vehicle (EV) Charger up to 50Amp, 240V, Indoor/Outdoor Car Charging Station with Level 2, Wi-Fi and Bluetooth Enabled EVSE, 25-Foot Cable(Dark Gray)

View on Amazon
REDTIGER 4K Dash Cam Front and Rear, STARVIS 2 Sensor, Touch Screen 3.18", 128GB Card Included, Voice Control, 5.8GHz WiFi Car Dash Camera, GPS, Night Vision, Emergency Lock, Parking Mode (F7N Touch)

REDTIGER 4K Dash Cam Front and Rear, STARVIS 2 Sensor, Touch Screen 3.18", 128GB Card Included, Voice Control, 5.8GHz WiFi Car Dash Camera, GPS, Night Vision, Emergency Lock, Parking Mode (F7N Touch)

View on Amazon

*As an Amazon Associate, we earn from qualifying purchases.

Technical Specifications

This subcompact cars features a 4.4L 8-cylinder engine, paired with a manual 6-spd transmission and rear-wheel drive drivetrain.

Maximizing Fuel Economy

To achieve the best fuel economy in your 2004 BMW 645ci Convertible, consider these tips:

  • Maintain steady speeds and avoid rapid acceleration
  • Keep tires properly inflated to manufacturer specifications
  • Remove excess weight and roof cargo when not needed
  • Follow recommended maintenance schedules

BMW 645ci Convertible manual 6-spd Historical Fuel Efficiency

Loading timeline data...

Compare & Calculate Your Fuel Savings

Estimate Fuel Savings Over Time

To embed this FREE calculator on your site, visit our fuel savings calculator page, and copy the embed code.

Vehicle 1

Vehicle 2

How Many Miles Do You Drive?

miles/year
monthly:1,250miles/month
weekly:288miles/week
daily:41miles/day

This Fuel Savings Calculator tool is provided for informational and educational purposes only. The MPG data used is sourced from the U.S. Environmental Protection Agency (EPA), an official government resource, and while efforts are made to ensure accuracy, discrepancies or updates may occur. Calculations are based on standard assumptions and estimates, which may not reflect individual circumstances or real-world conditions. Users are responsible for verifying results with their own data and should consult additional resources or/and professionals for critical decisions. This tool is provided "as is" without warranties of any kind, and the developers disclaim any liability for decisions or actions taken based on its output. The tool may be updated or modified without notice, affecting its functionality or results. By using this tool, you acknowledge and agree to these terms.

2004 BMW 645ci Convertible - Auto (S6)

Quick Summary

The 2004 BMW 645ci Convertible with auto (s6) has an estimated 19.0 MPG combined. This auto (s6) premium gasoline-powered vehicle offers 16.0 MPG in the city and 24.0 MPG on the highway.

Premium Gasoline Fuel Economy

Combined19.0 MPG

City16.0 MPG

Highway24.0 MPG

More Featured Products*

ChargePoint HomeFlex Level 2 EV Charger J1772, Hardwired for Electric Car - Fast Smart Battery Power Charging at Home for Electric Automobile Vehicles

ChargePoint HomeFlex Level 2 EV Charger J1772, Hardwired for Electric Car - Fast Smart Battery Power Charging at Home for Electric Automobile Vehicles

View on Amazon
Tesla Wall Connector - Electric Vehicle (EV) Charger - Level 2 - up to 48A with 24' Cable

Tesla Wall Connector - Electric Vehicle (EV) Charger - Level 2 - up to 48A with 24' Cable

View on Amazon
Autel Scanner MaxiCOM MK900: 2025 Same as MK900BT MK900-BT MX900 Bidirectional Diagnostic Tool, 8in Up of MK808S MK808BT Pro MX808S MK808Z, 3K+ Active Tests, 40+ Service, CAN-FD&DOIP, All System, FCA

Autel Scanner MaxiCOM MK900: 2025 Same as MK900BT MK900-BT MX900 Bidirectional Diagnostic Tool, 8in Up of MK808S MK808BT Pro MX808S MK808Z, 3K+ Active Tests, 40+ Service, CAN-FD&DOIP, All System, FCA

View on Amazon

*As an Amazon Associate, we earn from qualifying purchases.

Technical Specifications

This subcompact cars with auto (s6) features a 4.4L 8-cylinder engine and rear-wheel drive drivetrain.

More Featured Products*

ChargePoint HomeFlex Level 2 EV Charger J1772, Hardwired for Electric Car - Fast Smart Battery Power Charging at Home for Electric Automobile Vehicles

ChargePoint HomeFlex Level 2 EV Charger J1772, Hardwired for Electric Car - Fast Smart Battery Power Charging at Home for Electric Automobile Vehicles

View on Amazon
Tesla Wall Connector - Electric Vehicle (EV) Charger - Level 2 - up to 48A with 24' Cable

Tesla Wall Connector - Electric Vehicle (EV) Charger - Level 2 - up to 48A with 24' Cable

View on Amazon
Autel Scanner MaxiCOM MK900: 2025 Same as MK900BT MK900-BT MX900 Bidirectional Diagnostic Tool, 8in Up of MK808S MK808BT Pro MX808S MK808Z, 3K+ Active Tests, 40+ Service, CAN-FD&DOIP, All System, FCA

Autel Scanner MaxiCOM MK900: 2025 Same as MK900BT MK900-BT MX900 Bidirectional Diagnostic Tool, 8in Up of MK808S MK808BT Pro MX808S MK808Z, 3K+ Active Tests, 40+ Service, CAN-FD&DOIP, All System, FCA

View on Amazon

*As an Amazon Associate, we earn from qualifying purchases.

BMW 645ci Convertible auto (s6) Historical Fuel Efficiency

Loading timeline data...

2004 BMW 645ci Convertible - Auto (S6)

Quick Summary

The 2004 BMW 645ci Convertible with auto (s6) has an estimated 16.0 MPG combined. This auto (s6) premium gasoline-powered vehicle offers 13.0 MPG in the city and 21.0 MPG on the highway.

Premium Gasoline Fuel Economy

Combined16.0 MPG

City13.0 MPG

Highway21.0 MPG

More Featured Products*

ChargePoint HomeFlex Level 2 EV Charger J1772, Hardwired for Electric Car - Fast Smart Battery Power Charging at Home for Electric Automobile Vehicles

ChargePoint HomeFlex Level 2 EV Charger J1772, Hardwired for Electric Car - Fast Smart Battery Power Charging at Home for Electric Automobile Vehicles

View on Amazon
Tesla Wall Connector - Electric Vehicle (EV) Charger - Level 2 - up to 48A with 24' Cable

Tesla Wall Connector - Electric Vehicle (EV) Charger - Level 2 - up to 48A with 24' Cable

View on Amazon
Autel Scanner MaxiCOM MK900: 2025 Same as MK900BT MK900-BT MX900 Bidirectional Diagnostic Tool, 8in Up of MK808S MK808BT Pro MX808S MK808Z, 3K+ Active Tests, 40+ Service, CAN-FD&DOIP, All System, FCA

Autel Scanner MaxiCOM MK900: 2025 Same as MK900BT MK900-BT MX900 Bidirectional Diagnostic Tool, 8in Up of MK808S MK808BT Pro MX808S MK808Z, 3K+ Active Tests, 40+ Service, CAN-FD&DOIP, All System, FCA

View on Amazon

*As an Amazon Associate, we earn from qualifying purchases.

Technical Specifications

This subcompact cars with auto (s6) features a 4.4L 8-cylinder engine and rear-wheel drive drivetrain.

More Featured Products*

ChargePoint HomeFlex Level 2 EV Charger J1772, Hardwired for Electric Car - Fast Smart Battery Power Charging at Home for Electric Automobile Vehicles

ChargePoint HomeFlex Level 2 EV Charger J1772, Hardwired for Electric Car - Fast Smart Battery Power Charging at Home for Electric Automobile Vehicles

View on Amazon
Tesla Wall Connector - Electric Vehicle (EV) Charger - Level 2 - up to 48A with 24' Cable

Tesla Wall Connector - Electric Vehicle (EV) Charger - Level 2 - up to 48A with 24' Cable

View on Amazon
Autel Scanner MaxiCOM MK900: 2025 Same as MK900BT MK900-BT MX900 Bidirectional Diagnostic Tool, 8in Up of MK808S MK808BT Pro MX808S MK808Z, 3K+ Active Tests, 40+ Service, CAN-FD&DOIP, All System, FCA

Autel Scanner MaxiCOM MK900: 2025 Same as MK900BT MK900-BT MX900 Bidirectional Diagnostic Tool, 8in Up of MK808S MK808BT Pro MX808S MK808Z, 3K+ Active Tests, 40+ Service, CAN-FD&DOIP, All System, FCA

View on Amazon

*As an Amazon Associate, we earn from qualifying purchases.

BMW 645ci Convertible auto (s6) Historical Fuel Efficiency

Loading timeline data...

Vehicles With Similar Fuel Economy

16.0 MPG

2009 Audi S4 Cabriolet

View detailed fuel economy data

16.0 MPG

2013 BMW M3 Convertible

View detailed fuel economy data

16.0 MPG

2013 BMW M3 Coupe

View detailed fuel economy data

These vehicles are in the same class (Subcompact Cars) and offer comparable fuel economy ratings.

UNDER DEVELOPMENT

Road Trip Cost Calculator

Plan your journey, calculate fuel costs, and find routes & hotels with our interactive trip planner. Some features coming soon!

Try beta version
SAVE MONEY

Fuel Savings Calculator

Compare vehicles and see how much you could save with better fuel efficiency.

Calculate savings
COMPARE

Vehicle MPG Comparison

Compare fuel efficiency between different vehicles side by side.

Compare now
QUICK CHECK

Vehicle MPG Checker

Find the official fuel economy rating for any vehicle make and model.

Check a vehicle