Bradley L. Schulz, by his mother and natural guardian, Katherine Schulz,and Katherine Schulz, individually, Respondents, American Compensation Insurance Company, Intervenor, vs. Park 'N Go of Minnesota, et al., Appellants.

may not be cited except as provided by

Minn. Stat. § 480 A. 08, subd. 3 (1996).

 STATE OF MINNESOTA

 IN COURT OF APPEALS

 C3-97-1846

Loren Piepho, et al.,

Appellants,

vs.

Scott's Auto Repair, Inc., d/b/a Steve's Custom Rebuilt Engines,

Respondent.

 Filed March 24, 1998

 Affirmed

 Schumacher, Judge

Dakota County District Court

File No. C2969984

James R. Martin, 607 North Central Avenue, Faribault, MN 55021 (for appellants)

Arlene M. Asencio Perkkio, 155 South Wabasha Street, Suite 103, St. Paul, MN 55107 (for respondent)

Considered and decided by Schumacher, Presiding Judge, Huspeni, Judge, and Shumaker, Judge.

 U N P U B L I S H E D O P I N I O N

 SCHUMACHER, Judge

Appellants Loren and Genean Piepho contend the trial court erred when it enforced a contract, rejected their conversion claim, and denied their motion for judgment notwithstanding the verdict (JNOV) or, in the alternative, a new trial. We affirm.

 FACTS

This case arises out of a contract for automotive repairs between the Piephos and respondent Scott's Auto Repair, Inc., d/b/a Steve's Custom Rebuilt Engines (Scott's Auto). When the Piephos picked up their truck, they were prepared to pay for the repairs by cash and check. Scott's Auto, however, operated only on a cash or credit basis; Scott's Auto did not accept checks as a standard practice. Scott's Auto made an exception, however, and allowed the Piephos to pay $700 cash; $1,000 by check payable on June 27, 1996; a post-dated check for $1,128.41 payable on August 27, 1996; and a post-dated check for $1,100 payable on October 27, 1996. The total bill was $3,928.41, including a two-year/24,000 warranty.

When the Piephos picked up their truck, they signed a contract/work receipt that contained these provisions:

IN THE EVENT ANY CHECK I GIVE TO YOU IN PAYMENT FOR LABOR, SKILL AND MATERIAL IN REPAIRING THE ABOVE VEHICLE IS RETURNED TO YOU, UNPAID FOR ANY REASON, I FURTHER HEREBY GIVE YOU THE AUTHORITY AND RIGHT TO IMMEDIATELY RETAKE POSSESSION OF THE VEHICLE WHEREVER IT IS LOCATED, WITHOUT ANY NOTICE TO ME, AND TO HOLD AND DETAIN THE VEHICLE UNTIL PAYMENT IN FULL, IN CASH IS MADE TO YOU.

IF THE ABOVE NOTED VEHICLE IS REMOVED FROM THE PREMISES OF SCOTT'S AUTO REPAIR, INC. OR ANY PROPERTY THEREOF, WITHOUT PAYMENT IN FULL FOR ANY REASON I FURTHER HEREBY GIVE YOU THE AUTHORITY AND RIGHT TO IMMEDIATELY RETAKE POSSESSION OF THE ABOVE VEHICLE WHEREVER IT IS LOCATED, WITHOUT ANY NOTICE TO ME, AND TO HOLD AND DETAIN THE VEHICLE UNTIL PAYMENT IN FULL, IN CASH, IS MADE TO YOU.

Shortly thereafter, the Piephos had engine problems with the newly-repaired truck. Scott's Auto admitted that some of the items needing repair would have been covered under the warranty, but refused to perform at that point because no payment had been made for the underlying engine rebuild. When Scott's Auto declined to perform under the warranty, the Piephos stopped payment on the remaining post-dated checks, leaving Scott's Auto uncompensated for the balance of $2,228.41. Scott's Auto then repossessed the truck.

The Piephos alleged that, without their vehicle, they incurred damages for the loss of 6 stud fees ($3,600); the cost of 12 extra trips to haul hay ($500); the loss of transportation fees ($150); the loss of the use of their vehicle ($5,640); the loss of the value of the vehicle ($5,000); and attorney fees and trial preparation fees ($7,644). Their lawsuit alleged replevin, breach of contract, negligence, fraud, and conversion.

Shortly after filing the complaint, the Piephos moved the court to order Scott's Auto to return the truck to their possession. The court granted that order. When the remainder of the case was tried to the court, the court rejected the Piephos' claims for conversion, breach, negligence, and fraud, and determined that Scott's Auto was entitled to the $2,228.41 balance due on the initial contract for repairs. The court then denied the Piephos' motions for JNOV or a new trial. The Piephos appeal.

 D E C I S I O N

The decision to grant JNOV is a pure question of law. Edgewater Motels, Inc. v. Gatzke, 277 N.W.2d 11, 14 (Minn. 1979).

Unless we are able to determine that the evidence is practically conclusive against the verdict, or that reasonable minds could reach but one conclusion against the verdict, the trial court's order denying the motion for judgment notwithstanding the verdict should stand.

 Seidl v. Trollhaugen, Inc., 305 Minn. 506, 507, 232 N.W.2d 236, 239 (1975).

In contrast, the decision to grant a new trial rests within the sound discretion of the trial court and will not be overturned absent a clear abuse of that discretion. Halla Nursery v. Baumann-Furrie & Co., 454 N.W.2d 905, 910 (Minn. 1990). On appeal from the denial of a motion for a new trial, we must affirm unless the court's decision is manifestly and palpably contrary to the evidence, viewed in a light most favorable to the verdict. ZumBerge v. Northern States Power Co., 481 N.W.2d 103, 110 (Minn. App. 1992), review denied (Minn. Apr. 29, 1992).

The Piephos contend that Scott's Auto is liable for conversion because it repossessed the truck and deprived the Piephos of its use.

Conversion has been defined as an act of wilful interference with a chattel, done without lawful justification, by which any person entitled thereto is deprived of use and possession.

 Larson v. Archer-Daniels-Midland Co., 226 Minn. 315, 317, 32 N.W.2d 649, 650 (1948) quoted in Naegele v. Minneapolis Community Dev. Agency, 551 N.W.2d 235, 238 (Minn. App. 1996).

The Piephos seek to substantiate their claim by showing that Scott's Auto lacked lawful justification for repossessing the truck. They allege that the provision regarding repossession was a new element to the repair contract that had not been included in their negotiation and, thus, required additional consideration.

Consideration is an essential element for a valid contract. Deli v. Hasselmo, 542 N.W.2d 649, 656 (Minn. App. 1996), review denied (Minn. Apr. 16, 1996) (citing Baehr v. Penn-O-Tex Oil Corp., 258 Minn. 533, 538-39, 104 N.W.2d 661, 665 (1960)).

Consideration is something of value given in return for a performance or promise of performance that is bargained for; consideration is what distinguishes a contract from a gift.

 Id.

The flaw in the Piephos' argument is their misconstruction of their contract with Scott's Auto. The parties had created an executory contract, under which Scott's Auto agreed to rebuild the Piephos' Chevy engine. An executory contract leaves something yet to be done or agreed upon in the future, or depends on some future act or contingency of a party. Coates v. Cooper, 121 Minn. 11, 20, 140 N.W. 120, 124 (1913). An executory contract that is not within the statute of frauds may be modified, without independent consideration, and still be valid and binding on the parties. Asbestos Prods., Inc. v. Healy Mech. Contractors, Inc., 306 Minn. 74, 76, 235 N.W.2d 807, 808-09 (1975) (involving executory contract to insulate building; court enforced contract that included modified terms that parties had discussed and accepted, without additional consideration over and above work completed under contract).

When the Piephos knowingly signed the contract, they agreed to the provision allowing Scott's Auto to repossess the vehicle and bound themselves to those terms. They knew that failure of payment would lead to repossession of the vehicle. The Piephos chose to pay by post-dated check rather than explore other financing options, such as procuring a loan from a bank or commercial lender. The court assumes that the written contract encompasses the entire agreement of the parties. See Hoyt v. Brokaw, 359 N.W.2d 310, 311 (Minn. App. 1984) (written agreement supersedes all contract negotiations). The parties' agreement became a complete, executed contract when the Piephos signed the work receipt/contract and began paying the bill for services rendered. The mechanical services that Scott's Auto performed when rebuilding the engine served as the consideration for the agreement.

Scott's Auto also provided independent consideration by allowing the Piephos to leave the premises with their vehicle without paying in full. Scott's Auto essentially agreed to finance a $2228.41 interest-free loan and forego payment until the last post-dated check came due four months later.

This record supports the trial court's decision to enforce Scott's Auto's contract and reject the Piephos' conversion claim. The court's decision is not manifestly and palpably contrary to the evidence.

  Affirmed.