After more than 50 rentals, my grandpa and grandma have noticed that Enterprise CarShare's cars match manufacturer's advertised fuel economies, but Enterprise Rent-A-Car's are much lower. E.g., a CarShare's KIA Soul yielded 4-6 L/100 km, but Rent-A-Car's same model of KIA Soul yielded 13-15 L/100 km!

They suspect that as CarShare (a car sharing company) pays for gasoline, it cleans and services their cars better than Rent-A-Car, which requires renters to pay for gasoline and so has less incentive to keep cars fuel-efficient.

They drive identically on CarShare's and Rent-A-Car's cars. If anything, they'd expect worse fuel efficiency for CarShare's cars especially in the winter when they use the car heater.

  1. Is there any evidence for our suspicion? Has anyone experienced this difference?

  2. If our suspicion is true, then please see the question in the title. Starting with a fuel-efficient car is easier than requesting compensation after the trip.

  • 2
    I'm voting to close this question as off-topic.
    – Giorgio
    Nov 21 '18 at 12:08
  • 1
    This seems more like a call to activism than an objectively answerable question. Even though you're an experienced user of Stack Exchange, I would encourage you to read again the tour and help center because a lot of your questions at the moment are attracting close votes. Nov 21 '18 at 15:20
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    Also, manufacturers' fuel economy claims rarely have much to do with actual real-world driving Nov 21 '18 at 15:21
  • @DavidRicherby You're correct that I perhaps ought not to compare with manufacturer's claimed fuel economy, but what of my comparisons to CarShare?
    – NNOX Apps
    Nov 21 '18 at 18:04
  • Are you sure, that both cars are exactly the same model and the same fuel? 2,5 - 4 l/km sounds like a Diesel engine, 7-9 l/km fits to a gasoline engine.
    – dunni
    Nov 22 '18 at 7:57

I think the case is not related to maintenance. I think maintenance is equal in both cases. Many rental cars are sold back to the car manufacturer within 1 year in what is called a repurchase agreement. The manufacturer buys the car back with a daily depreciation and those go on to the brand's dealers. Cars that aren't under repurchase are sold to the public. Plus you have liability if an accident occurs and it is claimed the company failed to maintain the vehicle. In all cases, maintenance to manufacturer standards is necessary with records being kept.

Keep in mind too that a modern car under 30,000 miles should need nothing more than oil changes and tire inflation.

I'd argue that the difference is because the rental car is on average, newer than the car share. It is known that fuel efficiency is lower as moving parts wear in. Besides repurchase agreements, car share vehicles require installation of electronics and telemetry that incentivize keeping the car in the fleet longer.

So I think you should try to correlate fuel efficiency with odometer readings across both fleets.

  • Are there any other reasons? We don't think "that the difference is because the rental car is on average, newer than the car share. It is known that fuel efficiency is lower as moving parts wear in." In fact, CarShare's cars are often newer.
    – NNOX Apps
    Nov 22 '18 at 5:41

The answer to your *updated* title, how to demand that the car match the manufacturer's rated fuel economy - due to the factors listed towards the end, I don't believe this is feasible.

The answer to your immediate question; how to check before driving if the car matches a certain fuel economy rating; can be done by the following:

  • Turn on the car, check the on board trip computer. Almost all modern cars have a fuel economy readout which tells you what was the fuel economy on the last trip. However, if someone has reset the trip computer, this value may not be accurate.

  • Carry with you a OBD adapter and a cellphone app. Plug it into the OBD port and read the last fuel economy reading.

Practically speaking - car fuel economy ratings are like laptop or cellphone battery estimates - they are done in controlled conditions which rarely apply to real life use. Cars sometimes match, sometimes exceed, but often struggle to match the ratings.

The figures on the sticker are to be used as a guideline only - they are not hard numbers.

Saudi Arabia has introduced fuel economy rating stickers on new vehicles sold, which are also used in other countries in the GCC. Here is what it looks like:

sample sticker

As you can see, the number is more of a guideline of how good or poor is the fuel economy of the vehicle. The actual figure is as a result of controlled testing.

I don't have recent experience with Enterprise, but what I can tell you is I have rented the exact same car (in fact, ironically, it was even the same bland white color) from two different reputable international franchise rental agents from the airport in Bahrain. Each car performed differently when it came to fuel efficiency. There are many reasons for this:

  • Maintenance - a poorly maintained engine is not as efficient
  • The grade of fuel used, if different than what the car is rated for
  • The gearing / how you drive. If you constantly use the manual pedals, "sports mode", etc. this all affects the fuel economy.
  • Tire pressure
  • Driving with the windows up or down, AC on or off, etc.
  • Ambient temperature and altitude

I am not sure what can be done to reliably predict how a car will perform - short of actually driving it.

  • Thanks. I think the most relevant reason is "Maintenance - a poorly maintained engine is not as efficient". As I wrote in my post, the other factors aren't relevant.
    – NNOX Apps
    Nov 21 '18 at 18:05

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