This page contains Appendix D
of the paper "Defining Business Rules ~ What Are They Really?", produced
by the Business Rules Group. Other formats in which this paper is available are described
in Defining Business Rules -- What Are
They Really? (Abstract & Table of Contents)
Defining Business Rules ~ What Are They Really?
Appendix D - Case Study: EU-Rent Car
Examples in this document are based on the following Case Study. This case study
was developed by Model Systems, Ltd., along with several other organizations, and
has been used by other organizations. The material below may be copied and used freely,
if its source is clearly acknowledged.
EU-Rent Car Rentals
EU-Rent is a car rental company owned by EU-Corporation. It is one of three businesses
- the other two being hotels and an airline - that each has its own business and
IT systems, but with a shared customer base. Many of the car rental customers also
fly with EU-Fly and stay at EU-Stay hotels.
EU-Rent has 1000 branches in towns in several countries. At each branch cars,
classified by car group, are available for rental. Each branch has a manager and
booking clerks who handle rentals.
- Most rentals are by advance reservation; the rental period and the car group
are specified at the time of reservation. EU-Rent will also accept immediate ("walk-in")
rentals, if cars are available.
At the end of each day cars are assigned to reservations for the following day.
If more cars have been requested than are available in a group at a branch, the branch
manager may ask other branches if they have cars they can transfer to him.
- Cars rented from one branch of EU-Rent may be returned to a different branch.
The renting branch must ensure that the car has been returned to some branch at the
end of the rental period. If a car is returned to a branch other than the one that
rented it, ownership of the car is assigned to the new branch.
- EU-Rent also has service depots, each serving several branches. Cars may be booked
for maintenance at any time provided that the service depot has capacity on the day
For simplicity, only one booking per car per day is allowed. A rental or service
may cover several days.
- A customer can have several reservations but only one car rented at a time. EU-Rent
keeps records of customers, their rentals and bad experiences such as late return,
problems with payment and damage to cars. This information is used to decide whether
to approve a rental.
EU-Rent Business Rules
- Each driver authorized to drive the car during a rental must have a valid driver's
- Each driver authorized to drive the car during a rental must be insured to the
level required by the law of each country that may be visited during the rental.
- Rented cars must meet local legal requirements for mechanical condition and emissions
for each country that may be visited during the rental.
- Local tax must be collected (at the drop-off location) on the rental charge.
Rental reservation acceptance
- If a rental request does not specify a particular car group or model, the default
is group A (the lowest-cost group).
- Reservations may be accepted only up to the capacity of the pick-up branch on
the pick-up day.
- If the customer requesting the rental has been blacklisted, the rental must be
- A customer may have multiple future reservations, but may have only one car at
Car allocation for advance reservations
At the end of each working day, cars are allocated to rental requests due for
pick-up the following working day. The basic rules are applied within a branch:
- Only cars that are physically present in EU-Rent branches may be assigned.
- If a specific model has been requested, a car of that model should be assigned
if one is available. Otherwise, a car in the same group as the requested model should
- If no specific model has been requested, any car in the requested group may be
- The end date of the rental must be before any scheduled booking of the assigned
car for maintenance or transfer
- After all assignments within a group have been made, 10% of the group quota for
the branch (or all the remaining cars in the group, whichever number is lower) must
be reserved for the next day's walk-in rentals. Surplus capacity may be used for
- If there are not sufficient cars in a group to meet demand, a one-group free
upgrade may be given (i.e. a car of the next higher group may be assigned at the
same rental rate) if there is capacity
- Customers in the loyalty incentive scheme have priority for free upgrades.
If demand cannot be satisfied within a branch under the basic rules, one of the
'exception' options may be selected:
- A car may be allocated from the capacity reserved for the next day's walk-ins.
- A 'bumped upgrade' may be made. (For example, if a group A
car is needed and there is no capacity in group A or B, then a car allocated to a
group B reservation may be replaced by a group C car, and the freed-up group B car
allocated to the group A reservation.)
- A downgrade may be made.
- A "downgrade" is a car of a lower group.
- A car from another branch may be allocated, if there is a suitable car available
and there is time to transfer it to the pick-up branch.
- A car due for return the next day may be allocated, if there will be time to
prepare it for rental before the scheduled pick-up time.
- A car scheduled for service may be used, provided that the rental would not take
the mileage more than 10% over the normal mileage for service.
If demand cannot be satisfied within a branch under the 'exception' rules, one
of the 'in extremis' options may be selected:
- Pick-up may have to be delayed until a car is returned and prepared.
- A car may have to be rented from a competitor.
- The end date of the rental must be before any scheduled booking of the assigned
car for maintenance or transfer.
- If there are several available cars of the model or group requested, the one
with the lowest mileage should be allocated.
- Each driver authorized to drive the car during a rental must be over 25 and have
held a driver's license for at least one year.
- The credit card used to guarantee a rental must belong to one of the authorized
drivers; and this driver must sign the rental contract. Other drivers must sign an
'additional drivers authorization' form.
- The driver who signs the rental agreement must not currently have a EU-Rent car
- Before releasing the car, a credit reservation equivalent to the estimated rental
cost must be made against the guaranteeing credit card.
- The car must not be handed over to a driver who appears to be under the influence
of alcohol or drugs.
- The driver must be physically able to drive the car safely - must not be too
tall, too short or too fat; if disabled, must be able to operate the controls.
- The car must have been prepared -- cleaned, full tank of fuel, oil and water
topped up, tires properly inflated.
- The car must have been checked for roadworthiness -- tire tread depth, brake
pedal and hand brake lever travel, lights, exhaust leaks, windscreen wipers.
- If an assigned car has not been picked up 90 minutes after the scheduled pick-up
time, it may be released for walk-in rental, unless the rental has been guaranteed
by credit card.
- If a rental has been guaranteed by credit card and the car has not been picked
up by the end of the scheduled pick-up day, one day's rental is charged to the credit
card and the car is released for use the following day.
Return from rental
- At the end of a rental, the customer may pay by cash, or by a credit card other
than the one used to guarantee the rental.
- If a car is returned to a location other than the agreed drop-off branch, a drop-off
penalty is charged.
- The car must be checked for wear (brakes, lights, tires, exhaust, wipers etc.)
and damage, and repairs scheduled if necessary.
- If the car has been damaged during the rental and the customer is liable, the
customer's credit card company must be notified of a pending charge.
- If a car is returned early, the rental charge is calculated at the rate appropriate
to the actual period of rental (e.g. daily rate rather than weekly).
- If the car is returned late, an hourly charge is made up to 6 hours' delay; after
6 hours a whole day is charged.
- A customer may request a rental extension by phone -- the extension should be
granted unless the car is scheduled for maintenance.
- If a car is not returned from rental by the end of the scheduled drop-off day
and the customer has not arranged an extension, the customer should be contacted.
- If a car is three days overdue and the customer has not arranged an extension,
insurance cover lapses and the police must be informed.
Car maintenance & repairs
- Each car must be serviced every three months or 10,000 kilometers, whichever
- If there is a shortage of cars for rental, routine maintenance may be delayed
by up to 10% of the time or distance interval (whichever was the basis for scheduling
maintenance) to meet rental demand.
- Cars needing repairs (other than minor body scratches and dents) must not bus
used for rentals.
Car purchase and sale
- Only cars on the authorized list can be purchased.
- Cars are to be sold when they reach one year old or 40,000 kilometers, whichever
- A branch cannot refuse to accept a drop-off of a EU-Rent car, even if a one-way
rental has not been authorised.
- When a car is dropped off at a branch other than the pick-up branch, the car's
ownership (and, hence, responsibility for it) switches to the drop-off branch when
the car is dropped off.
- When a transfer of a car is arranged between branches, the car's ownership switches
to the 'receiving' branch when the car is picked up.
- In each car group, if a branch accumulates cars to take it more than 10% over
its quota, it must reduce the number back to within 10% of quota by transferring
cars to other branches or selling some cars.
- In each car group, if a branch loses cars to take it more than 10% below its
quota, it must increase the number back to within 10% of quota by transferring cars
from other branches or buying some cars.
Loyalty incentive scheme
- To join the loyalty incentive scheme, a customer must have made 4 rentals within
- Each paid rental in the scheme (including the 4 qualifying rentals) earns points
that may be used to buy 'free rentals.'
- Only the basic rental cost of a free rental can be bought with points. Extras,
such as insurance, fuel and taxes must be paid by cash or credit card.
- A free rental must be booked at least fourteen days before the pick-up date.
- Free rentals do not earn points.
- Unused points expire three years after the end of the year in which they were
Examples of "rules for running the business"
(not really the same kind of rules as those above)
- Each branch must be set targets for performance -- numbers of rentals, utilization
of cars, turnover, profit, customer satisfaction, etc.
- Where performance requirements conflict (e.g. profit vs customer satisfaction
when a customer requests a reduction in charges after an unsatisfactory rental) heuristics
must be provided to guide branch staff.
- Performance data must be captured.
If performance targets are not met, control action must be taken. Control action
- changing the resources at branches (e.g. numbers of cars, quotas of cars within
each group, number of staff),
- changing responsibilities (e.g. having transfers of cars managed by groups of
branches, rather than by negotiation between individual branch managers),
- changing operational guidance (e.g. what proportion of cars should be kept for
walk-in rentals), but not external constraints (e.g. legal requirements) or company
policies (e.g. rentals must be guaranteed by a credit card, a customer may have only
one car at a time).
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