If you`re concerned about fuel economy but the mini Geo Metro fits like a corset, there`s a host of high-mileage cars on the market that skimp on gaswithout skimping on the simple pleasures.

A trio of `91 small cars arrived for testing-the Nissan Sentra andChevrolet Corsica and Cavalier-each carrying an above-average mileage rating, but none of which has to be hidden behind the recycling bin in the garage for fear the neighbors will label you cheap.

Sentra is all-new for 1991 and Corsica and Cavalier are carryover modelswith minimum change.

We drove the performance Sentra SE-R, which is offered only as a two-door coupe and only with 5-speed manual; the Corsica LT four-door sedan with 4-speed automatic (5-speed manual standard); and the two-door Cavalier VL(for value leader) coupe with 5-speed manual (3-speed automatic optional).

Of the two cars we drove with manual, the Sentra 5-speed was a pleasure-smooth easy movement with no notchiness, balkiness or hesitation. The 5-speed in the Cavalier became more arthritic and loud the more we drove.There`s only one smooth 5-speed in the GM stable, and that`s in the Saturn.

In overall performance, the Sentra also stood out. The 2-liter, 16-valve, 140-horsepower, 4-cylinder engine is the one offered in the new Infiniti G20from Nissan`s luxury division, which means it`s quick yet quiet, a livelynumber that skips away from the light ahead of the pack but still is rated at 24 miles per gallon city/32 m.p.g. highway.

Base engine in Corsica is a 2.2-liter, 4-cylinder. Our test car came with the optional ($685) 3.1-liter V-6 that develops the same 140-h.p. as theSentra`s 4-cylinder, but has to move about 300 more pounds.

The 3.1 is lively teamed with the optional 4-speed automatic ($540), butSentra`s 16-valve 4 is quicker. The 3.1 carries a 20-m.p.g. city/27-m.p.g.highway rating. With 5-speed manual the rating is 19 m.p.g. city/28 m.p.g.highway.

Look at those numbers a second. With automatic you get 1 m.p.g. more than the manual in the city and only 1 m.p.g. less on the highway. Is 1 m.p.g. moreon the highway worth suffering through five gears in rush-hour traffic?

The Cavalier VL was equipped with a 2.2-liter, 95-h.p., 4-cylinderdesigned for mileage. When moving from the light, the VL seemed impressive,until we realized exhaust sound effects made the engine appear more livelythan it was. If a 24 m.p.g. city/35 m.p.g. highway mileage rating is moreimportant than a 0- to 60-m.p.h. time, the 2.2 liter serves its purpose. With automatic ($465), the 2.2-liter 4 is rated at 24/32.

Ride and handling again finds Sentra the leader. Smooth without beingmushy, firm without being harsh. Sentra sits fairly tight and flat on thepavement in turns and corners. Corsica also is smooth, but you detect moresway and lean in turns and corners. Cavalier offers adequate ride andhandling. You`ll find the center console comes in handy as an elbow rest when making a turn and you and the car lean.

For safety, Sentra offers antilock brakes as a $700 option, but no airbags. Corsica offers driver-side air bag as standard, but not antilock brakes.Cavalier offers neither.

Roominess is about the same in all three. Good room up front, butslightly tight leg and head room in back, especially in the Sentra andCavalier coupes. In all, the cargo or trunk area was massive for holdingluggage or groceries.

The styling nod goes to Sentra. The Japanese subcompact for too longlacked visual substance-a tin can on wheels. The `91 remake is rounder andmore aerodynamic and a pleasant-looking number. The SE-R adds a sporty decklid spoiler. Sentra is built on the same 95.7-inch wheelbase as the `90 model,but is two inches longer at 170.3 inches. Those two extra inches look like twoadded feet.

Corsica is one of the more style-conscious Chevy models. It gets goodmileage without looking like an economy ca r. One glance, especially in allblack with red striping; it looks like a little luxury car.

Cavalier needs a design overhaul.

As for price, Cavalier is the winner with a base of $7,995 for the two-door VL coupe.

Standard equipment includes power brakes and steering; bodyside moldings; 14-inch, steel-belted, radial tires; remote driver`s mirror; and stainlesssteel exhaust.

Our test car added electric rear-window defroster for $160; airconditioning for $730; and a preferred equipment package consisting of AM-FMstereo with digital clock, color keyed mats, dual mirrors (left remote) andtinted glass for $500. With a $455 freight charge, the sticker read $9,840.

The Corsica LT sedan had a $10,070 base.

Standard equipment included power brakes and steering; driver`s side airbag; tinted glass; stainless steel exhaust; AM/FM stereo with digital clock;14-inch, steel-belted radials; and intermittent wipers.

Added were rear-window defroster at $160; automatic transmission at $540; 3.1-liter V-6 at $685; sport-handling suspension for $395; and a preferedoption package including air, AM-FM stereo with cassette and clock, powerwindows, power door locks, speed control, tilt wheel, intermittent wipers,power hatch release, and color-keyed carpeted mats for $2,036 (minus a $600discount). After adding a few more gingerbread items, such as a gauge package for $139, the sticker came to $13,660. Add $455 for freight.

The Sentra SE-R starts at $10,970.

Standard equipment includes power brakes and steering; tilt wheel; remote trunk/fuel filler lid/hood release; rear- and side-window defrosters; sport-tuned suspension with front and rear stabilizer bars; intermittent wipers;14-inch, steel-belted radials; and fog lamps.

Options are minimal. Add $700 for antilock, $825 for air, $800 for apower sunroof and $50 for a leather-wrapped steering wheel, which brought the sticker on the test car to $13,345 plus $275 for freight. Any radio isoptional.

The most serious flaw of the three was up in Sentra. The sewn lipsurrounding the carpeted floor mats is too thick. We depressed the clutch toshift and when we released the pedal, it caught on that thick carpet lip,sticking to the floor. Not a pleasant situation. After moving the mat to head off the problem, it bunched up under the gas pedal.