The Short Answer
All three are good cars and the lease market treats them as interchangeable. What separates them is not the driving, it is what you can actually find out before you sign.
The BMW X3 publishes the most complete data and has the most recent Euro NCAP result, tested in 2024 on the current car. The Mercedes GLC publishes good data but its five-star rating is from 2022 and does not cover the plug-in hybrid most people lease. The Audi Q5 drives well and is the hardest of the three to compare, because Audi UK does not publish WLTP economy, CO2, boot capacity or towing weights on its own configurator at all.
If you want the car with the fewest unanswered questions, that is the X3. If you want the best looking cabin, most people say the Audi. We would rather tell you which one you can verify than pretend there is a single winner.
You Cannot Properly Compare These Three on the Manufacturers' Own Websites
This is the part no comparison article mentions, and it is the thing that would actually have changed how we shopped.
Audi does not publish the numbers
Audi UK's Q5 pages carry performance figures and equipment lists but no WLTP combined economy, no CO2 figure, no boot capacity in litres and no towing weights. Those numbers exist, because they have to for type approval and for company car tax, but you will not find them on the page where you choose the car.
BMW leaves a model off its own spec page
BMW UK's X3 specification page does not list the 20d diesel. The launch press release lists it, Euro NCAP tested it, and BMW's own used and stock sites advertise it. So the diesel X3 is on sale and missing from the place you would look for it.
Mercedes publishes the most, and it is still not enough
Mercedes gives full WLTP data including the 50 g/km figure for the GLC 300 e. What it does not make obvious is that the five-star Euro NCAP rating shown against the GLC was achieved on a petrol car in 2022, and the plug-in hybrid is not covered by it.
If a broker or a comparison site shows you a clean table with all three cars' CO2, economy and boot space side by side, some of those Audi numbers have come from somewhere other than Audi. They may well be right. But they are not the manufacturer's published figures, and nobody tells you which is which.
The BMW X3 30e's CO2 Nearly Tripled, and the Car Did Not Change
The X3 30e plug-in hybrid was homologated at 24 g/km. The same car, with the same 19.7kWh battery, is now rated between 64 and 68 g/km depending on specification.
Nothing was taken off the car. What changed is the test. Euro 6e-bis revised the utility factor used to work out how much of a plug-in hybrid's driving is assumed to be electric, and the assumption became considerably less generous. Every plug-in hybrid retested under it has moved the same way.
For a company car driver that matters a great deal more than it sounds, because CO2 is what sets the benefit in kind band. We have written about where that leads in the PHEV company car tax cliff most directors have not noticed yet, and the thresholds are worth checking against your own figures with an accountant rather than taken from any article, including ours.
The Mercedes GLC 300 e sits at 50 g/km. The X3 30e sits in the mid sixties. Those two numbers were much closer to each other a year ago, and that gap is a testing change rather than an engineering one.
What the Euro NCAP Ratings Actually Cover
All three carry five stars. They are not the same five stars.
| Car | Tested | What the rating covers |
|---|---|---|
| BMW X3 | 2024 | The current generation, tested under the most recent protocol of the three |
| Mercedes GLC | 2022 | A petrol GLC. The GLC 300 e plug-in hybrid is not covered by this result |
| Audi Q5 | 2021 generation result | Check the specific result against the car you are quoted on, because the range has been revised since |
A rating also has a shelf life. Euro NCAP results now expire, and a lapsed rating does not mean a car is unsafe, it means it has not been assessed against the current protocol. We have set out how that works, and which popular lease cars have lapsed, in our piece on Euro NCAP ratings expiring.
None of this makes the GLC a bad car. It means that if safety rating is one of your reasons for choosing it, you should check that the rating belongs to the version you are leasing.
How They Compare on the Things You Can Verify
| Audi Q5 | BMW X3 | Mercedes GLC | |
|---|---|---|---|
| Plug-in hybrid offered | Yes | Yes, 30e | Yes, 300 e |
| Diesel offered | Yes | Yes, 20d, though not on BMW's spec page | Yes |
| WLTP CO2 published by the maker | No | Yes | Yes |
| Boot capacity published by the maker | No | Yes | Yes |
| Towing weights published by the maker | No | Yes | Yes |
| Most recent Euro NCAP test | 2021 generation | 2024 | 2022, petrol only |
We have deliberately left out range, economy and boot figures for the Q5 rather than fill the gaps from a source Audi does not stand behind. If those numbers matter to your decision, ask for them in writing against the exact specification you are being quoted.
Which One Would We Lease?
On the evidence rather than the badge:
The X3 if you want the fewest unknowns. Most recent crash test, full published data, and the diesel still exists if you do the mileage to justify it.
The GLC if you want the plug-in hybrid and you have checked the CO2 figure against your own tax position, because 50 g/km sits near a boundary that matters and one gram either side of it is not a rounding error.
The Q5 if you have driven all three and prefer it, which plenty of people do. Just get the missing numbers confirmed in writing first.
All three are also worth comparing against the rest of the segment rather than only against each other, because the premium mid-size SUV class is the most crowded part of the market.
Compare These Three Directly
Current lease pricing on each of the cars in this article.
Worth Reading Before You Decide
The guides that cover the money rather than the metal.
Want the Numbers Audi Will Not Print?
We will get the CO2, economy, boot and towing figures confirmed in writing against the exact specification you are quoted on, before you commit to anything.
Talk to LetsLeaseFrequently Asked Questions
On what you can actually verify, the BMW X3. It publishes complete data and has the most recent Euro NCAP test, carried out in 2024 on the current car. The GLC publishes good data but its five star rating is from 2022 and does not cover the plug-in hybrid. The Q5 drives well and is the hardest of the three to check, because Audi UK does not publish WLTP economy, CO2, boot capacity or towing weights at all.
We do not know, and Audi does not say. The figures exist, because they are required for type approval and for company car tax. They are simply absent from Audi UK's own configurator and model pages. If a comparison table shows you Q5 CO2 or boot figures, those have come from somewhere other than Audi, and nobody tells you which numbers are which.
The car did not change. The X3 30e was homologated at 24 g/km and is now rated between 64 and 68 g/km on the same 19.7kWh battery. Euro 6e-bis revised the utility factor used to estimate how much of a plug-in hybrid's driving is electric, and the new assumption is much less generous. Every plug-in hybrid retested under it has moved the same way.
No. The five star result was achieved on a petrol GLC in 2022. The GLC 300 e plug-in hybrid is not covered by it. The rating is also due to expire around December 2028. If the safety rating is part of why you are choosing the car, check that it belongs to the version you are being quoted on.
Yes, the 20d. It is missing from BMW UK's own X3 specification page, which is why people think it has gone, but the launch press release lists it, Euro NCAP tested it and BMW's own stock site advertises it. If you want the diesel, ask for it by name rather than assuming it is unavailable.
That depends on your own CO2 and tax position rather than on the car, and the figures have moved recently enough that older advice is unreliable. The GLC 300 e sits at 50 g/km and the X3 30e in the mid sixties, and those two numbers were much closer a year ago. Get the exact CO2 for your quoted specification in writing and check it with your accountant.
Yes. The Q5 is offered as a plug-in hybrid, the X3 as the 30e and the GLC as the 300 e. All three were affected by the Euro 6e-bis testing change, so compare current CO2 figures rather than any you remember from a year or two ago.