Model years, miles and mpg: read specifications accurately

Two accurate specification sheets can still produce a misleading comparison. One may use a different model year, another a different test cycle, and a third may describe optional equipment as if it were standard. International Bentley reading becomes clearer when you check the context before comparing the numbers.

Keep a simple rule: every important figure needs a unit, a vehicle specification and a source. If one is missing, the answer is incomplete. A recent-looking article title does not supply the missing information.

Separate the dates

An announcement date, production date, model year and first registration are not the same thing. A vehicle can be registered after its production period or described by a model year that differs from the calendar year in which it was built. Confirm which date the document is using.

When discussing a generation change, allow for market differences and overlapping registrations. Do not identify a car's full specification from its number plate year or from a photograph alone. Use the original vehicle information where available.

Keep distance units visible

One mile is approximately 1.609 kilometres. A recorded 10,000 miles is therefore about 16,100 kilometres, not 10,000 kilometres. Retain the original unit in a service timeline and label any conversion. Rounding is appropriate for a travel illustration but should not replace an original odometer record.

The same care applies to speed. Sixty miles per hour is approximately 97 kilometres per hour; it is not identical to 100 kilometres per hour. Acceleration claims for 0–60 mph and 0–100 km/h describe different endpoints and should not be treated as directly identical tests.

Be careful with mpg

US and Imperial gallons have different volumes. A UK mpg number and a US mpg number can differ even when describing the same fuel use. Litres per 100 kilometres is another format, in which a lower number indicates less fuel used over that distance.

For reference, L/100 km is approximately 235.215 divided by US mpg, or 282.481 divided by Imperial mpg. These conversions change units; they do not make different laboratory test procedures equivalent. Do not convert a plug-in hybrid's headline figure and assume it describes an uncharged long-distance journey.

Name the equipment and market

An option available in one country may not be offered in another, and a feature available on a model family may not be fitted to the vehicle being discussed. Record the actual equipment and the evidence for it. Use “not confirmed” where the documentation is incomplete.

Price comparisons also need an explicit currency and a statement about included taxes or fees. Converting currency alone does not account for differences in specification, local charges or quotation dates. Avoid presenting a converted foreign price as a local quotation.

Keep a conversion sheet beside the comparison

The last two rows show a substantial apparent discrepancy produced entirely by units. Conversely, converting two figures to L/100 km does not prove that the cars underwent the same test or carried the same equipment.

Use four labels with a quoted performance figure: model/derivative, market, unit and test description. Keep manufacturer claims distinct from an independent measured result. A headline that shortens “0–100 km/h” to “0–60” has changed the claim, even if the writer intended only to translate it for another audience.

For power figures, preserve the source's designation such as PS, bhp or kW rather than silently calling every number “horsepower.” If you need a converted comparison, use a documented conversion and show both values. Precision is useful only when the underlying descriptions match.

A good international article makes these differences easy to see. It should not force a reader in the USA, Canada or UK to guess which gallon, currency or model-year convention the author intended.

These checks may seem small, but they prevent large misunderstandings. Once the dates, units and specification align, the numbers become useful. Until then, the most responsible comparison is to make the differences visible rather than hide them behind a neat table.